Last tested: 24 Jul, 2018
npm-check (latest)
Published 07 Jul, 2018
No known vulnerabilities in npm-check
Security wise, npm-check seems to be a safe package to use.
Over time, new vulnerabilities may be disclosed on npm-check and other packages. To easily find, fix and prevent such vulnerabilties, protect your repos with Snyk!
Vulnerable versions of npm-check
Fixed in 5.7.1
Prototype Pollution
Detailed paths
- Introduced through: npm-check@5.7.0 > merge-options@0.0.64
Overview
Affected versions of merge-options 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('merge-options');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';
var a = {};
console.log("Before : " + a.oops);
merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);
Remediation
Upgrade merge-options
to version 1.0.1 or higher.
References
Fixed in 5.0.1
Prototype Pollution
Detailed paths
- Introduced through: npm-check@4.1.4 > lodash@3.10.1
- Introduced through: npm-check@4.1.4 > inquirer@0.11.4 > lodash@3.10.1
Overview
lodash is a javaScript utility library delivering modularity, performance & extras.
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 _= require('lodash');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';
var a = {};
console.log("Before : " + a.oops);
_.merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);
Remediation
Upgrade lodash
to version 4.17.5 or higher.
References
Fixed in 4.1.0
Regular Expression Denial of Service (DoS)
Detailed paths
- Introduced through: glob@4.0.4 > minimatch@0.3.0
- Introduced through: npm-check@4.0.4 > depcheck@0.4.7 > minimatch@2.0.10
Overview
minimatch
is a minimalistic matching library used for converting glob expressions into JavaScript RegExp objects.
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks.
The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Many Regular Expression implementations may reach edge cases that causes them to work very slowly (exponentially related to input size), allowing an attacker to exploit this and can cause the program to enter these extreme situations by using a specially crafted input and cause the service to excessively consume CPU, resulting in a Denial of Service.
An attacker can provide a long value to the minimatch
function, which nearly matches the pattern being matched. This will cause the regular expression matching to take a long time, all the while occupying the event loop and preventing it from processing other requests and making the server unavailable (a Denial of Service attack).
You can read more about Regular Expression Denial of Service (ReDoS)
on our blog.
Remediation
Upgrade minimatch
to version 3.0.2
or greater.
References
Fixed in 4.0.2
Arbitrary Code Injection
Detailed paths
- Introduced through: npm-check@4.0.1 > mocha@2.5.3 > growl@1.9.2
Overview
growl
is a package adding Growl support for Nodejs.
Affected versions of the package are vulnerable to Arbitrary Code Injection due to unsafe use of the eval()
function. Node.js provides the eval()
function by default, and is used to translate strings into Javascript code. An attacker can craft a malicious payload to inject arbitrary commands.
Remediation
Upgrade growl
to version 1.10.0 or higher.
References
Regular Expression Denial of Service (ReDoS)
Detailed paths
- Introduced through: mongoose@4.0.1 > mquery@1.4.0 > debug@0.7.4
- Introduced through: npm-check@4.0.1 > mocha@2.5.3 > debug@2.2.0
Overview
debug
is a JavaScript debugging utility modelled after Node.js core's debugging technique..
debug
uses printf-style formatting. Affected versions of this package are vulnerable to Regular expression Denial of Service (ReDoS) attacks via the the %o
formatter (Pretty-print an Object all on a single line). It used a regular expression (/\s*\n\s*/g
) in order to strip whitespaces and replace newlines with spaces, in order to join the data into a single line. This can cause a very low impact of about 2 seconds matching time for data 50k characters long.
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:
- CCC
- CC+C
- C+CC
- 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 debug
to version 2.6.9, 3.1.0 or higher.
References
Regular Expression Denial of Service (ReDoS)
Detailed paths
- Introduced through: mongoose@4.0.1 > ms@0.1.0
- Introduced through: npm-check@4.0.1 > mocha@2.5.3 > debug@2.2.0 > ms@0.7.1
Overview
ms
is a tiny millisecond conversion utility.
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to an incomplete fix for previously reported vulnerability npm:ms:20151024. The fix limited the length of accepted input string to 10,000 characters, and turned to be insufficient making it possible to block the event loop for 0.3 seconds (on a typical laptop) with a specially crafted string passed to ms()
function.
Proof of concept
ms = require('ms');
ms('1'.repeat(9998) + 'Q') // Takes about ~0.3s
Note: Snyk's patch for this vulnerability limits input length to 100 characters. This new limit was deemed to be a breaking change by the author. Based on user feedback, we believe the risk of breakage is very low, while the value to your security is much greater, and therefore opted to still capture this change in a patch for earlier versions as well. Whenever patching security issues, we always suggest to run tests on your code to validate that nothing has been broken.
For more information on Regular Expression Denial of Service (ReDoS)
attacks, go to our blog.
Disclosure Timeline
- Feb 9th, 2017 - Reported the issue to package owner.
- Feb 11th, 2017 - Issue acknowledged by package owner.
- April 12th, 2017 - Fix PR opened by Snyk Security Team.
- May 15th, 2017 - Vulnerability published.
- May 16th, 2017 - Issue fixed and version
2.0.0
released. - May 21th, 2017 - Patches released for versions
>=0.7.1, <=1.0.0
.
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:
- CCC
- CC+C
- C+CC
- 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 ms
to version 2.0.0 or higher.
References
Fixed in 3.2.9
Prototype Pollution
Detailed paths
- Introduced through: npm-check@3.2.7 > registry-url@2.1.0 > rc@0.5.5 > deep-extend@0.2.11
Overview
Affected versions of deep-extend 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);
Remediation
Upgrade deep-extend
to version 0.5.1 or higher.
References
Fixed in 3.0.0
Regular Expression Denial of Service (ReDoS)
Detailed paths
- Introduced through: npm@2.0.0 > semver@4.0.3
- Introduced through: hapi@2.0.0 > semver@2.2.1
- Introduced through: npm-check@2.0.0 > semver-diff@1.0.0 > semver@3.0.1
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
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:
- CCC
- CC+C
- C+CC
- 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
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
Fixed in 1.0.0
Uninitialized Memory Exposure
Detailed paths
- Introduced through: npm-check@0.0.4 > npmconf@1.1.9
Overview
Affected versions of npmconf are vulnerable to Uninitialized Memory Exposure. It allocates and writes to disk uninitialized memory content when a typed number is passed as input.
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.
Note npmconf
is deprecated and should not be used.
Note This is vulnerable only for Node <=4
References
Fixed in 0.0.4
Prototype Pollution
Detailed paths
- Introduced through: browserify@0.0.3 > npm@6.2.0 > libcipm@2.0.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > libcipm@2.0.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > libcipm@2.0.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5 > boom@2.10.1 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > libcipm@2.0.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > sntp@1.0.9 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > sntp@1.0.9 > hoek@2.16.3
- Introduced through: browserify@0.0.3 > npm@6.2.0 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > sntp@1.0.9 > hoek@2.16.3
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1 > hoek@0.9.1
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1 > boom@0.4.2 > hoek@0.9.1
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1 > cryptiles@0.2.2 > boom@0.4.2 > hoek@0.9.1
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1 > sntp@0.2.4 > hoek@0.9.1
Overview
hoek is a 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);
Remediation
Upgrade hoek
to versions 4.2.1, 5.0.3 or higher.
References
Regular Expression Denial of Service (DoS)
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1
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:
- CCC
- CC+C
- C+CC
- 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
Uninitialized Memory Exposure
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > tunnel-agent@0.4.3
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
Access Restriction Bypass
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29
Overview
npm is a JavaScript package manager.
Affected versions of this package are vulnerable to Access Restriction Bypass. It might allow local users to bypass intended filesystem access restrictions due to ownerships of /etc
and /usr
directories are being changed unexpectedly, related to a "correctMkdir" issue.
Remediation
Upgrade npm
to version 5.7.1 or higher.
References
Remote Memory Exposure
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0
Overview
request
is a simplified http request client.
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.
If a direct dependency update is not possible, use snyk wizard
to patch this vulnerability.
References
Insecure Randomness
Detailed paths
- Introduced through: browserify@0.0.3 > npm@6.2.0 > libcipm@2.0.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5
- Introduced through: browserify@0.0.3 > npm@6.2.0 > npm-lifecycle@2.0.3 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5
- Introduced through: browserify@0.0.3 > npm@6.2.0 > node-gyp@3.7.0 > request@2.81.0 > hawk@3.1.3 > cryptiles@2.0.5
- Introduced through: npm-check@0.0.3 > changelog@1.4.2 > request@2.83.0 > hawk@6.0.2 > cryptiles@3.1.2
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > hawk@1.1.1 > cryptiles@0.2.2
Overview
cryptiles is a package for general crypto utilities.
Affected versions of this package are vulnerable to Insecure Randomness. The randomDigits()
method is supposed to return a cryptographically strong pseudo-random data string, but it was biased to certain digits. An attacker could be able to guess the created digits.
Remediation
Upgrade to version 4.1.2 and higher.
References
npm Token Leak
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29
Overview
This vulnerability could cause the unintentional leakage of bearer tokens. A design flaw in npm's registry allows an attacker to set up an HTTP server that could collect authentication information, and then use this authentication information to impersonate the users whose tokens they collected. The attacker could do anything the compromised users could do, including publishing new versions of packages.
Details
The primary npm registry has, since late 2014, used HTTP bearer tokens to authenticate requests from the npm command-line interface. Due to a design flaw in the CLI, these bearer tokens were sent with every request made by logged-in users, regardless of the destination of the request. (The bearers only should have been included for requests made against a registry or registries used for the current install.)
This flaw allows an attacker to set up an HTTP server that could collect authentication information. They could then use this information to impersonate the users whose tokens they collected. This impersonation would allow them to do anything the compromised users could do, including publishing new versions of packages.
With the fixes npm have released, the CLI will only send bearer tokens with requests made against a registry. npm’s CLI team believe that the fix won’t break any existing registry setups. However, it’s possible the change will be breaking in some cases, due to the large number of registry software suites used.
Remediation
- Upgrade npm to ">= 3.8.3 || >= 2.15.1"
- Invalidate your current npm bearer tokens
References
Symlink File Overwrite
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > node-gyp@1.0.3 > tar@1.0.3
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > tar@1.0.3
Overview
The tar
module prior to version 2.0.0 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 to version 2.0.0 or greater.
If a direct dependency update is not possible, use snyk wizard
to patch this vulnerability.
References
Prototype Override Protection Bypass
Detailed paths
- Introduced through: cordova@0.0.3 > express@3.0.6 > connect@2.7.2 > qs@0.5.1
- Introduced through: hapi@0.0.3 > express@2.5.11 > qs@0.4.2
- Introduced through: angular@0.0.3 > express@2.5.10 > qs@0.4.2
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > qs@1.2.2
Overview
qs
is a querystring parser that supports nesting and arrays, with a depth limit.
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
and6.0.4
Remediation
Upgrade qs
to version 6.4.0
or higher.
Note: The fix was backported to the following versions 6.3.2
, 6.2.3
, 6.1.2
, 6.0.4
.
References
Regular Expression Denial of Service (ReDoS)
Detailed paths
- Introduced through: cordova@0.0.3 > express@3.0.6 > connect@2.7.2 > send@0.1.0 > mime@1.2.6
- Introduced through: cordova@0.0.3 > express@3.0.6 > send@0.1.0 > mime@1.2.6
- Introduced through: hapi@0.0.3 > express@2.5.11 > mime@1.2.4
- Introduced through: angular@0.0.3 > express@2.5.10 > mime@1.2.4
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > form-data@0.1.4 > 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.
The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Many Regular Expression implementations may reach extreme situations that cause them to work very slowly (exponentially related to input size), allowing an attacker to exploit this and can cause the program to enter these extreme situations by using a specially crafted input and cause the service to excessively consume CPU, resulting in a Denial of Service.
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:
- CCC
- CC+C
- C+CC
- 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 versions 1.4.1, 2.0.3 or higher.
References
Timing Attack
Detailed paths
- Introduced through: npm-check@0.0.3 > npm@1.4.29 > request@2.42.0 > http-signature@0.10.1
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.