npmd@0.20.3

Vulnerabilities

34 via 147 paths

Dependencies

299

Source

npm

Find, fix and prevent vulnerabilities in your code.

Severity
  • 19
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  • 3
Status
  • 34
  • 0
  • 0

high severity
new

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: ansi-regex
  • Introduced through: npm-registry-client@0.2.31

Detailed paths

  • Introduced through: npmd@0.20.3 npm-registry-client@0.2.31 npmlog@5.0.1 gauge@3.0.1 strip-ansi@4.0.0 ansi-regex@3.0.0
  • Introduced through: npmd@0.20.3 npm-registry-client@0.2.31 npmlog@5.0.1 gauge@3.0.1 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
  • Introduced through: npmd@0.20.3 npm-registry-client@0.2.31 npmlog@5.0.1 gauge@3.0.1 wide-align@1.1.3 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0

Overview

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to the sub-patterns [[\\]()#;?]* and (?:;[-a-zA-Z\\d\\/#&.:=?%@~_]*)*.

PoC

import ansiRegex from 'ansi-regex';

for(var i = 1; i <= 50000; i++) {
    var time = Date.now();
    var attack_str = "\u001B["+";".repeat(i*10000);
    ansiRegex().test(attack_str)
    var time_cost = Date.now() - time;
    console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade ansi-regex to version 6.0.1, 5.0.1 or higher.

References

high severity

Remote Memory Exposure

  • Vulnerable module: bl
  • Introduced through: level@0.18.0

Detailed paths

  • Introduced through: npmd@0.20.3 level@0.18.0 level-packager@0.18.0 levelup@0.18.6 bl@0.8.2
    Remediation: Upgrade to npmd@1.0.2.

Overview

bl is a library that allows you to collect buffers and access with a standard readable buffer interface.

Affected versions of this package are vulnerable to Remote Memory Exposure. If user input ends up in consume() argument and can become negative, BufferList state can be corrupted, tricking it into exposing uninitialized memory via regular .slice() calls.

PoC by chalker

const { BufferList } = require('bl')
const secret = require('crypto').randomBytes(256)
for (let i = 0; i < 1e6; i++) {
  const clone = Buffer.from(secret)
  const bl = new BufferList()
  bl.append(Buffer.from('a'))
  bl.consume(-1024)
  const buf = bl.slice(1)
  if (buf.indexOf(clone) !== -1) {
    console.error(`Match (at ${i})`, buf)
  }
}

Remediation

Upgrade bl to version 2.2.1, 3.0.1, 4.0.3, 1.2.3 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: deep-extend
  • Introduced through: level-manifest@1.1.1, rc@0.3.5 and others

Detailed paths

  • Introduced through: npmd@0.20.3 level-manifest@1.1.1 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 rc@0.3.5 deep-extend@0.2.11
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 multilevel@4.1.0 level-manifest@1.1.1 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-bin@1.2.2 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 deep-extend@0.2.11

Overview

deep-extend is a library for Recursive object extending.

Affected versions of this package are vulnerable to Prototype Pollution. Utilities function in all the listed modules can be tricked into modifying the prototype of "Object" when the attacker control part of the structure passed to these function. This can let an attacker add or modify existing property that will exist on all object.

PoC by HoLyVieR

var merge = require('deep-extend');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';

var a = {};
console.log("Before : " + a.oops);
merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade deep-extend to version 0.5.1 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: ecstatic
  • Introduced through: ecstatic@0.4.13

Detailed paths

  • Introduced through: npmd@0.20.3 ecstatic@0.4.13
    Remediation: Upgrade to npmd@1.0.2.

Overview

ecstatic is a simple static file server middleware. Use it with a raw http server, express/connect or on the CLI.

Affected versions of this package are vulnerable to Denial of Service (DoS). It is possible to crash a server using the package due to the way URL params parsing is handled during redirect.

PoC

curl --path-as-is $(echo -e -n "http://127.0.0.1:8080/existing-dir-name?\x0cfoo")

In the PoC the library is trying to redirect /existing-dir-name?\x0cfoo to /existing-dir-name/?\x0cfoo which cause TypeError: The header content contains invalid characters error because of \x0c symbol.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade ecstatic to version 4.1.4 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: ecstatic
  • Introduced through: ecstatic@0.4.13

Detailed paths

  • Introduced through: npmd@0.20.3 ecstatic@0.4.13
    Remediation: Upgrade to npmd@1.0.2.

Overview

ecstatic is a simple static file server middleware. Use it with a raw http server, express/connect or on the CLI.

Affected versions of this package are vulnerable to Denial of Service (DoS). The vulnerability is caused by the combination of two bugs. First, the underlying V8 engine throws an exception when processing the specially crafted date, instead of stating the date is invalid as it should. Second, the ecstatic server does not handle the exception, triggering the crash.

Upgrading Ecstatic will address the second issue and thus fix the vulnerability.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade ecstatic to version 1.4.0 or higher.

References

high severity

Arbitrary File Overwrite

  • Vulnerable module: fstream
  • Introduced through: npmd-install@4.2.6, npmd-resolve@5.4.2 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 fstream@0.1.31
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20 fstream@0.1.31
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 fstream@0.1.31
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 fstream@0.1.31
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18 fstream@0.1.31
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17 fstream@0.1.31
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20 fstream@0.1.31
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20 fstream@0.1.31

Overview

fstream is a package that supports advanced FS Streaming for Node.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. Extracting tarballs containing a hardlink to a file that already exists in the system and a file that matches the hardlink will overwrite the system's file with the contents of the extracted file.

Remediation

Upgrade fstream to version 1.0.12 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: ini
  • Introduced through: npmconf@0.1.16, rc@0.3.5 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmconf@0.1.16 ini@1.1.0
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 rc@0.3.5 ini@1.1.0
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-bin@1.2.2 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 ini@1.1.0

Overview

ini is an An ini encoder/decoder for node

Affected versions of this package are vulnerable to Prototype Pollution. If an attacker submits a malicious INI file to an application that parses it with ini.parse, they will pollute the prototype on the application. This can be exploited further depending on the context.

PoC by Eugene Lim

payload.ini

[__proto__]
polluted = "polluted"

poc.js:

var fs = require('fs')
var ini = require('ini')

var parsed = ini.parse(fs.readFileSync('./payload.ini', 'utf-8'))
console.log(parsed)
console.log(parsed.__proto__)
console.log(polluted)
> node poc.js
{}
{ polluted: 'polluted' }
{ polluted: 'polluted' }
polluted

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade ini to version 1.3.6 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: minimatch
  • Introduced through: npmd-rebuild@0.1.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 glob@3.2.11 minimatch@0.3.0
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 minimatch@0.4.0

Overview

minimatch is a minimal matching utility.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via complicated and illegal regexes.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade minimatch to version 3.0.2 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: minimatch
  • Introduced through: npmd-rebuild@0.1.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 glob@3.2.11 minimatch@0.3.0
    Remediation: Open PR to patch minimatch@0.3.0.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 minimatch@0.4.0
    Remediation: Open PR to patch minimatch@0.4.0.

Overview

minimatch is a minimal matching utility.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS).

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade minimatch to version 3.0.2 or higher.

References

high severity

Uninitialized Memory Exposure

  • Vulnerable module: npmconf
  • Introduced through: npmconf@0.1.16

Detailed paths

  • Introduced through: npmd@0.20.3 npmconf@0.1.16
    Remediation: Upgrade to npmd@1.3.1.

Overview

npmconf is a package to reintegrate directly into npm.

Affected versions of this package are vulnerable to Uninitialized Memory Exposure. It allocates and writes to disk uninitialized memory content when a typed number is passed as input.

Note npmconf is deprecated and should not be used. Note This is vulnerable only for Node <=4

Details

The Buffer class on Node.js is a mutable array of binary data, and can be initialized with a string, array or number.

const buf1 = new Buffer([1,2,3]);
// creates a buffer containing [01, 02, 03]
const buf2 = new Buffer('test');
// creates a buffer containing ASCII bytes [74, 65, 73, 74]
const buf3 = new Buffer(10);
// creates a buffer of length 10

The first two variants simply create a binary representation of the value it received. The last one, however, pre-allocates a buffer of the specified size, making it a useful buffer, especially when reading data from a stream. When using the number constructor of Buffer, it will allocate the memory, but will not fill it with zeros. Instead, the allocated buffer will hold whatever was in memory at the time. If the buffer is not zeroed by using buf.fill(0), it may leak sensitive information like keys, source code, and system info.

Remediation

Upgrade npmconf to version 2.1.3 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: qs
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 qs@0.6.6
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 qs@0.6.6
    Remediation: Open PR to patch qs@0.6.6.

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

Affected versions of this package are vulnerable to Denial of Service (DoS). During parsing, the qs module may create a sparse area (an array where no elements are filled), and grow that array to the necessary size based on the indices used on it. An attacker can specify a high index value in a query string, thus making the server allocate a respectively big array. Truly large values can cause the server to run out of memory and cause it to crash - thus enabling a Denial-of-Service attack.

Remediation

Upgrade qs to version 1.0.0 or higher.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

References

high severity

Prototype Override Protection Bypass

  • Vulnerable module: qs
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 qs@0.6.6
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 qs@0.6.6

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

Affected versions of this package are vulnerable to Prototype Override Protection Bypass. By default qs protects against attacks that attempt to overwrite an object's existing prototype properties, such as toString(), hasOwnProperty(),etc.

From qs documentation:

By default parameters that would overwrite properties on the object prototype are ignored, if you wish to keep the data from those fields either use plainObjects as mentioned above, or set allowPrototypes to true which will allow user input to overwrite those properties. WARNING It is generally a bad idea to enable this option as it can cause problems when attempting to use the properties that have been overwritten. Always be careful with this option.

Overwriting these properties can impact application logic, potentially allowing attackers to work around security controls, modify data, make the application unstable and more.

In versions of the package affected by this vulnerability, it is possible to circumvent this protection and overwrite prototype properties and functions by prefixing the name of the parameter with [ or ]. e.g. qs.parse("]=toString") will return {toString = true}, as a result, calling toString() on the object will throw an exception.

Example:

qs.parse('toString=foo', { allowPrototypes: false })
// {}

qs.parse("]=toString", { allowPrototypes: false })
// {toString = true} <== prototype overwritten

For more information, you can check out our blog.

Disclosure Timeline

  • February 13th, 2017 - Reported the issue to package owner.
  • February 13th, 2017 - Issue acknowledged by package owner.
  • February 16th, 2017 - Partial fix released in versions 6.0.3, 6.1.1, 6.2.2, 6.3.1.
  • March 6th, 2017 - Final fix released in versions 6.4.0,6.3.2, 6.2.3, 6.1.2 and 6.0.4

    Remediation

    Upgrade qs to version 6.0.4, 6.1.2, 6.2.3, 6.3.2 or higher.

    References

  • GitHub Commit
  • GitHub Issue

high severity

Arbitrary File Overwrite

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. This is due to insufficient symlink protection. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created.

This logic is insufficient when extracting tar files that contain both a directory and a symlink with the same name as the directory. This order of operations results in the directory being created and added to the node-tar directory cache. When a directory is present in the directory cache, subsequent calls to mkdir for that directory are skipped. However, this is also where node-tar checks for symlinks occur. By first creating a directory, and then replacing that directory with a symlink, it is possible to bypass node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and subsequently extracting arbitrary files into that location.

Remediation

Upgrade tar to version 3.2.3, 4.4.15, 5.0.7, 6.1.2 or higher.

References

high severity

Arbitrary File Overwrite

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. This is due to insufficient absolute path sanitization.

node-tar aims to prevent extraction of absolute file paths by turning absolute paths into relative paths when the preservePaths flag is not set to true. This is achieved by stripping the absolute path root from any absolute file paths contained in a tar file. For example, the path /home/user/.bashrc would turn into home/user/.bashrc.

This logic is insufficient when file paths contain repeated path roots such as ////home/user/.bashrc. node-tar only strips a single path root from such paths. When given an absolute file path with repeating path roots, the resulting path (e.g. ///home/user/.bashrc) still resolves to an absolute path.

Remediation

Upgrade tar to version 3.2.2, 4.4.14, 5.0.6, 6.1.1 or higher.

References

high severity

Arbitrary File Overwrite

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. Extracting tarballs containing a hard-link to a file that already exists in the system, and a file that matches the hard-link may overwrite system's files with the contents of the extracted file.

Remediation

Upgrade tar to version 2.2.2, 4.4.2 or higher.

References

high severity
new

Arbitrary File Write

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Write. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created.

This logic was insufficient when extracting tar files that contained both a directory and a symlink with the same name as the directory, where the symlink and directory names in the archive entry used backslashes as a path separator on posix systems. The cache checking logic used both \ and / characters as path separators. However, \ is a valid filename character on posix systems.

By first creating a directory, and then replacing that directory with a symlink, it is possible to bypass node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location. This can lead to extracting arbitrary files into that location, thus allowing arbitrary file creation and overwrite.

Additionally, a similar confusion could arise on case-insensitive filesystems. If a tar archive contained a directory at FOO, followed by a symbolic link named foo, then on case-insensitive file systems, the creation of the symbolic link would remove the directory from the filesystem, but not from the internal directory cache, as it would not be treated as a cache hit. A subsequent file entry within the FOO directory would then be placed in the target of the symbolic link, thinking that the directory had already been created.

Remediation

Upgrade tar to version 6.1.7, 5.0.8, 4.4.16 or higher.

References

high severity
new

Arbitrary File Write

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Write. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created.

This logic is insufficient when extracting tar files that contain two directories and a symlink with names containing unicode values that normalized to the same value. Additionally, on Windows systems, long path portions would resolve to the same file system entities as their 8.3 "short path" counterparts. A specially crafted tar archive can include directories with two forms of the path that resolve to the same file system entity, followed by a symbolic link with a name in the first form, lastly followed by a file using the second form. This leads to bypassing node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and extracting arbitrary files into that location.

Remediation

Upgrade tar to version 6.1.9, 5.0.10, 4.4.18 or higher.

References

high severity
new

Arbitrary File Write

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Arbitrary File Write. node-tar aims to guarantee that any file whose location would be outside of the extraction target directory is not extracted. This is, in part, accomplished by sanitizing absolute paths of entries within the archive, skipping archive entries that contain .. path portions, and resolving the sanitized paths against the extraction target directory.

This logic is insufficient on Windows systems when extracting tar files that contain a path that is not an absolute path, but specify a drive letter different from the extraction target, such as C:some\path. If the drive letter does not match the extraction target, for example D:\extraction\dir, then the result of path.resolve(extractionDirectory, entryPath) resolves against the current working directory on the C: drive, rather than the extraction target directory.

Additionally, a .. portion of the path can occur immediately after the drive letter, such as C:../foo, and is not properly sanitized by the logic that checks for .. within the normalized and split portions of the path.

Note: This only affects users of node-tar on Windows systems.

Remediation

Upgrade tar to version 6.1.9, 5.0.10, 4.4.18 or higher.

References

high severity

Symlink File Overwrite

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
    Remediation: Open PR to patch tar@0.1.18.
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
    Remediation: Open PR to patch tar@0.1.17.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
    Remediation: Open PR to patch tar@0.1.20.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20
    Remediation: Open PR to patch tar@0.1.20.

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Symlink File Overwrite. It does not properly normalize symbolic links pointing to targets outside the extraction root. As a result, packages may hold symbolic links to parent and sibling directories and overwrite those files when the package is extracted.

Remediation

Upgrade tar to version 2.0.0 or higher.

References

medium severity

Uninitialized Memory Exposure

  • Vulnerable module: bl
  • Introduced through: level@0.18.0

Detailed paths

  • Introduced through: npmd@0.20.3 level@0.18.0 level-packager@0.18.0 levelup@0.18.6 bl@0.8.2
    Remediation: Upgrade to npmd@1.0.2.

Overview

bl is a storage object for collections of Node Buffers.

A possible memory disclosure vulnerability exists when a value of type number is provided to the append() method and results in concatenation of uninitialized memory to the buffer collection.

This is a result of unobstructed use of the Buffer constructor, whose insecure default constructor increases the odds of memory leakage.

Details

Constructing a Buffer class with integer N creates a Buffer of length N with raw (not "zero-ed") memory.

In the following example, the first call would allocate 100 bytes of memory, while the second example will allocate the memory needed for the string "100":

// uninitialized Buffer of length 100
x = new Buffer(100);
// initialized Buffer with value of '100'
x = new Buffer('100');

bl's append function uses the default Buffer constructor as-is, making it easy to append uninitialized memory to an existing list. If the value of the buffer list is exposed to users, it may expose raw server side memory, potentially holding secrets, private data and code. This is a similar vulnerability to the infamous Heartbleed flaw in OpenSSL.

const BufferList = require('bl')

var bl = new BufferList()
bl.append(new Buffer('abcd'))
bl.append(new Buffer('efg'))
bl.append('100')
// appends a Buffer holding 100 bytes of uninitialized memory
bl.append(100)                     
bl.append(new Buffer('j'))

You can read more about the insecure Buffer behavior on our blog.

Similar vulnerabilities were discovered in request, mongoose, ws and sequelize.

Note This is vulnerable only for Node <=4

References

medium severity

Time of Check Time of Use (TOCTOU)

  • Vulnerable module: chownr
  • Introduced through: npm-registry-client@0.2.31

Detailed paths

  • Introduced through: npmd@0.20.3 npm-registry-client@0.2.31 chownr@0.0.2
    Remediation: Upgrade to npmd@1.0.2.

Overview

chownr is a package that takes the same arguments as fs.chown()

Affected versions of this package are vulnerable to Time of Check Time of Use (TOCTOU). Affected versions of this package are vulnerable toTime of Check Time of Use (TOCTOU) attacks.

It does not dereference symbolic links and changes the owner of the link, which can trick it into descending into unintended trees if a non-symlink is replaced by a symlink at a critical moment:

      fs.lstat(pathChild, function(er, stats) {
        if (er)
          return cb(er)
        if (!stats.isSymbolicLink())
          chownr(pathChild, uid, gid, then)

Remediation

Upgrade chownr to version 1.1.0 or higher.

References

medium severity

Denial of Service (DoS)

  • Vulnerable module: ecstatic
  • Introduced through: ecstatic@0.4.13

Detailed paths

  • Introduced through: npmd@0.20.3 ecstatic@0.4.13
    Remediation: Upgrade to npmd@1.0.2.

Overview

ecstatic is a simple static file server middleware. Use it with a raw http server, express/connect or on the CLI.

Affected versions of this package are vulnerable to Denial of Service (DoS). The process of replacing null bytes in the url string is being done in a loop:

Find Null Bytes --> If found remove Null Byte --> Repeat

When no more Null Bytes found, the flow of the program continues.

This method would work fine with a normal URL that should be relatively short, but a malicious user may craft a very long URL with a lot of Null Bytes.

PoC by Checkmarx:

http://www.checkmarx.com/advisories/%00%00%00%00%00%00...

Slowdown:

A payload of 22kB caused a lag of 1 second, A payload of 35kB caused a lag of 3 seconds, A payload of 86kB caused the server to crash

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade ecstatic to version 2.0.0 or higher.

References

medium severity

Open Redirect

  • Vulnerable module: ecstatic
  • Introduced through: ecstatic@0.4.13

Detailed paths

  • Introduced through: npmd@0.20.3 ecstatic@0.4.13
    Remediation: Upgrade to npmd@1.0.2.

Overview

ecstatic is a simple static file server middleware. Use it with a raw http server, express/connect or on the CLI.

Affected versions of this package are vulnerable to Open Redirect. The package failed to validate redirects, allowing attackers to craft requests that result in an HTTP 301 redirect to any other domains.

Remediation

Upgrade ecstatic to version 2.2.2, 3.3.2, 4.1.2 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: hoek
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 hawk@0.13.1 boom@0.4.2 hoek@0.9.1
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 hawk@0.13.1 sntp@0.2.4 hoek@0.9.1
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 hawk@1.0.0 hoek@0.9.1
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 hawk@0.13.1 cryptiles@0.2.2 boom@0.4.2 hoek@0.9.1
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 hawk@1.0.0 boom@0.4.2 hoek@0.9.1
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 hawk@1.0.0 sntp@0.2.4 hoek@0.9.1
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 hawk@1.0.0 cryptiles@0.2.2 boom@0.4.2 hoek@0.9.1
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 hawk@0.13.1 hoek@0.8.5
    Remediation: Upgrade to npmd@1.0.2.

Overview

hoek is an Utility methods for the hapi ecosystem.

Affected versions of this package are vulnerable to Prototype Pollution. The utilities function allow modification of the Object prototype. If an attacker can control part of the structure passed to this function, they could add or modify an existing property.

PoC by Olivier Arteau (HoLyVieR)

var Hoek = require('hoek');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';

var a = {};
console.log("Before : " + a.oops);
Hoek.merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade hoek to version 4.2.1, 5.0.3 or higher.

References

medium severity

Timing Attack

  • Vulnerable module: http-signature
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 http-signature@0.10.1
    Remediation: Open PR to patch http-signature@0.10.1.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 http-signature@0.9.11
    Remediation: Upgrade to npmd@1.0.2.

Overview

http-signature is a reference implementation of Joyent's HTTP Signature scheme.

Affected versions of the package are vulnerable to Timing Attacks due to time-variable comparison of signatures.

The library implemented a character to character comparison, similar to the built-in string comparison mechanism, ===, and not a time constant string comparison. As a result, the comparison will fail faster when the first characters in the signature are incorrect. An attacker can use this difference to perform a timing attack, essentially allowing them to guess the signature one character at a time.

You can read more about timing attacks in Node.js on the Snyk blog.

Remediation

Upgrade http-signature to version 1.0.0 or higher.

References

medium severity

Unsigned Request Headers

  • Vulnerable module: http-signature
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 http-signature@0.9.11
    Remediation: Upgrade to npmd@1.0.2.

Overview

http-signature is a Reference implementation of Joyent's HTTP Signature scheme. Affected versions of the package are vulnerable to header forgery, due to the header names not being signed. An attacker could switch the header list order and header value order ending up wit the same signature for two separate requests.

Remediation

Upgrade http-signature to version 0.10.0 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: minimist
  • Introduced through: optimist@0.6.1, rc@0.3.5 and others

Detailed paths

  • Introduced through: npmd@0.20.3 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 rc@0.3.5 minimist@0.0.10
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-bin@1.2.2 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-tree@3.3.4 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-bin@1.2.2 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-tree@3.3.4 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-tree@3.3.4 npmd-config@1.0.12 optimist@0.6.1 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-tree@3.3.4 npmd-config@1.0.12 rc@0.3.5 minimist@0.0.10

Overview

minimist is a parse argument options module.

Affected versions of this package are vulnerable to Prototype Pollution. The library could be tricked into adding or modifying properties of Object.prototype using a constructor or __proto__ payload.

PoC by Snyk

require('minimist')('--__proto__.injected0 value0'.split(' '));
console.log(({}).injected0 === 'value0'); // true

require('minimist')('--constructor.prototype.injected1 value1'.split(' '));
console.log(({}).injected1 === 'value1'); // true

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade minimist to version 0.2.1, 1.2.3 or higher.

References

medium severity

Denial of Service (DoS)

  • Vulnerable module: qs
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 qs@0.6.6
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 qs@0.6.6
    Remediation: Open PR to patch qs@0.6.6.

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

Affected versions of this package are vulnerable to Denial of Service (DoS). When parsing a string representing a deeply nested object, qs will block the event loop for long periods of time. Such a delay may hold up the server's resources, keeping it from processing other requests in the meantime, thus enabling a Denial-of-Service attack.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade qs to version 1.0.0 or higher.

References

medium severity

Remote Memory Exposure

  • Vulnerable module: request
  • Introduced through: level-couch-sync@1.2.3 and npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 level-couch-sync@1.2.3 follow@0.8.0 request@2.2.9
    Remediation: Open PR to patch request@2.2.9.
  • Introduced through: npmd@0.20.3 level-couch-sync@1.2.3 request@2.14.0
    Remediation: Open PR to patch request@2.14.0.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0
    Remediation: Open PR to patch request@2.27.0.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0
    Remediation: Upgrade to npmd@1.0.2.

Overview

request is a simplified http request client.

Affected versions of this package are vulnerable to Remote Memory Exposure. A potential remote memory exposure vulnerability exists in request. If a request uses a multipart attachment and the body type option is number with value X, then X bytes of uninitialized memory will be sent in the body of the request.

Note that while the impact of this vulnerability is high (memory exposure), exploiting it is likely difficult, as the attacker needs to somehow control the body type of the request. One potential exploit scenario is when a request is composed based on JSON input, including the body type, allowing a malicious JSON to trigger the memory leak.

Details

Constructing a Buffer class with integer N creates a Buffer of length N with non zero-ed out memory. Example:

var x = new Buffer(100); // uninitialized Buffer of length 100
// vs
var x = new Buffer('100'); // initialized Buffer with value of '100'

Initializing a multipart body in such manner will cause uninitialized memory to be sent in the body of the request.

Proof of concept

var http = require('http')
var request = require('request')

http.createServer(function (req, res) {
  var data = ''
  req.setEncoding('utf8')
  req.on('data', function (chunk) {
    console.log('data')
    data += chunk
  })
  req.on('end', function () {
    // this will print uninitialized memory from the client
    console.log('Client sent:\n', data)
  })
  res.end()
}).listen(8000)

request({
  method: 'POST',
  uri: 'http://localhost:8000',
  multipart: [{ body: 1000 }]
},
function (err, res, body) {
  if (err) return console.error('upload failed:', err)
  console.log('sent')
})

Remediation

Upgrade request to version 2.68.0 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: semver
  • Introduced through: semver@2.2.1, add-deps@1.2.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 semver@2.2.1
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 add-deps@1.2.0 semver@2.2.1
    Remediation: Open PR to patch semver@2.2.1.
  • Introduced through: npmd@0.20.3 padded-semver@2.0.5 semver@2.2.1
    Remediation: Open PR to patch semver@2.2.1.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 semver@2.2.1
    Remediation: Open PR to patch semver@2.2.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 semver@2.2.1
    Remediation: Open PR to patch semver@2.2.1.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 padded-semver@2.0.5 semver@2.2.1
    Remediation: Open PR to patch semver@2.2.1.
  • Introduced through: npmd@0.20.3 npm-registry-client@0.2.31 semver@2.3.2
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmconf@0.1.16 semver@2.3.2
    Remediation: Upgrade to npmd@1.3.1.
  • Introduced through: npmd@0.20.3 level@0.18.0 level-packager@0.18.0 levelup@0.18.6 semver@2.3.2
    Remediation: Upgrade to npmd@1.0.2.

Overview

semver is a semantic version parser used by npm.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS).

Overview

npm is a package manager for javascript.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). The semver module uses regular expressions when parsing a version string. For a carefully crafted input, the time it takes to process these regular expressions is not linear to the length of the input. Since the semver module did not enforce a limit on the version string length, an attacker could provide a long string that would take up a large amount of resources, potentially taking a server down. This issue therefore enables a potential Denial of Service attack. This is a slightly differnt variant of a typical Regular Expression Denial of Service (ReDoS) vulnerability.

Details

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Remediation

Update to a version 4.3.2 or greater. From the issue description [2]: "Package version can no longer be more than 256 characters long. This prevents a situation in which parsing the version number can use exponentially more time and memory to parse, leading to a potential denial of service."

References

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade semver to version 4.3.2 or higher.

References

medium severity

Uninitialized Memory Exposure

  • Vulnerable module: tunnel-agent
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 tunnel-agent@0.3.0
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 tunnel-agent@0.3.0

Overview

tunnel-agent is HTTP proxy tunneling agent. Affected versions of the package are vulnerable to Uninitialized Memory Exposure.

A possible memory disclosure vulnerability exists when a value of type number is used to set the proxy.auth option of a request request and results in a possible uninitialized memory exposures in the request body.

This is a result of unobstructed use of the Buffer constructor, whose insecure default constructor increases the odds of memory leakage.

Details

Constructing a Buffer class with integer N creates a Buffer of length N with raw (not "zero-ed") memory.

In the following example, the first call would allocate 100 bytes of memory, while the second example will allocate the memory needed for the string "100":

// uninitialized Buffer of length 100
x = new Buffer(100);
// initialized Buffer with value of '100'
x = new Buffer('100');

tunnel-agent's request construction uses the default Buffer constructor as-is, making it easy to append uninitialized memory to an existing list. If the value of the buffer list is exposed to users, it may expose raw server side memory, potentially holding secrets, private data and code. This is a similar vulnerability to the infamous Heartbleed flaw in OpenSSL.

Proof of concept by ChALkeR

require('request')({
  method: 'GET',
  uri: 'http://www.example.com',
  tunnel: true,
  proxy:{
      protocol: 'http:',
      host:"127.0.0.1",
      port:8080,
      auth:80
  }
});

You can read more about the insecure Buffer behavior on our blog.

Similar vulnerabilities were discovered in request, mongoose, ws and sequelize.

Remediation

Upgrade tunnel-agent to version 0.6.0 or higher. Note This is vulnerable only for Node <=4

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: hawk
  • Introduced through: npmd-resolve@5.4.2

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 hawk@1.0.0
    Remediation: Open PR to patch hawk@1.0.0.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 hawk@0.13.1
    Remediation: Upgrade to npmd@1.0.2.

Overview

hawk is an HTTP authentication scheme using a message authentication code (MAC) algorithm to provide partial HTTP request cryptographic verification.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

You can read more about Regular Expression Denial of Service (ReDoS) on our blog.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: mime
  • Introduced through: ecstatic@0.4.13, level-couch-sync@1.2.3 and others

Detailed paths

  • Introduced through: npmd@0.20.3 ecstatic@0.4.13 mime@1.2.11
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 level-couch-sync@1.2.3 request@2.14.0 mime@1.2.11
    Remediation: Open PR to patch mime@1.2.11.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 mime@1.2.11
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 level-couch-sync@1.2.3 request@2.14.0 form-data@0.0.10 mime@1.2.11
    Remediation: Open PR to patch mime@1.2.11.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 mime@1.2.11
    Remediation: Open PR to patch mime@1.2.11.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 request@2.21.0 form-data@0.0.8 mime@1.2.11
    Remediation: Upgrade to npmd@1.0.2.
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 request@2.27.0 form-data@0.1.4 mime@1.2.11
    Remediation: Open PR to patch mime@1.2.11.

Overview

mime is a comprehensive, compact MIME type module.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). It uses regex the following regex /.*[\.\/\\]/ in its lookup, which can cause a slowdown of 2 seconds for 50k characters.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade mime to version 1.4.1, 2.0.3 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: tar
  • Introduced through: npmd-install@4.2.6, npmd-link@2.0.0 and others

Detailed paths

  • Introduced through: npmd@0.20.3 npmd-install@4.2.6 npmd-unpack@1.0.11 tar@0.1.18
  • Introduced through: npmd@0.20.3 npmd-link@2.0.0 npmd-unpack@1.0.1 tar@0.1.17
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 tar@0.1.20
    Remediation: Upgrade to npmd-resolve@6.0.1.
  • Introduced through: npmd@0.20.3 npmd-rebuild@0.1.2 node-gyp@0.12.2 tar@0.1.20
  • Introduced through: npmd@0.20.3 npmd-resolve@5.4.2 npmd-git-resolve@2.2.4 tar@0.1.20

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). When stripping the trailing slash from files arguments, the f.replace(/\/+$/, '') performance of this function can exponentially degrade when f contains many / characters resulting in ReDoS.

This vulnerability is not likely to be exploitable as it requires that the untrusted input is being passed into the tar.extract() or tar.list() array of entries to parse/extract, which would be unusual.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade tar to version 6.1.4, 5.0.8, 4.4.16 or higher.

References