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Overview

mongoose is a Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.

Affected versions of this package are vulnerable to Improper Neutralization of Special Elements in Data Query Logic due to the improper handling of $where in match queries. An attacker can manipulate search queries to inject malicious code.

Remediation

Upgrade mongoose to version 6.13.5, 7.8.3, 8.8.3 or higher.

References

• GitHub Commit
• GitHub Commit
• Nuclei Templates

Overview

mongoose is a Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.

Affected versions of this package are vulnerable to Improper Neutralization of Special Elements in Data Query Logic due to the improper use of a $where filter in conjunction with the populate() match. An attacker can manipulate search queries to retrieve or alter information without proper authorization by injecting malicious input into the query.

Note: This vulnerability derives from an incomplete fix of CVE-2024-53900

Remediation

Upgrade mongoose to version 6.13.6, 7.8.4, 8.9.5 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• GitHub Release
• Nuclei Templates

Overview

Affected versions of this package are vulnerable to Incomplete Cleanup in the makeMiddleware() function in make-middleware.js. An attacker can cause resource exhaustion by sending malformed requests.

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 multer to version 2.1.0 or higher.

References

• GitHub Commit
• Vendor Advisory

Overview

Affected versions of this package are vulnerable to Missing Release of Memory after Effective Lifetime due to improper handling of error events in HTTP request streams, which fails to close the internal busboy stream. An attacker can cause a denial of service by repeatedly triggering errors in file upload streams, leading to resource exhaustion and memory leaks.

Note:

This is only exploitable if the server is handling file uploads.

Remediation

Upgrade multer to version 2.0.0 or higher.

References

• GitHub Commit
• GitHub PR

Overview

Affected versions of this package are vulnerable to Missing Release of Resource after Effective Lifetime in the makeMiddleware() function, when dropping a connection during file upload. An attacker can cause resource exhaustion.

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 multer to version 2.1.0 or higher.

References

• GitHub Commit
• Vendor Advisory

Overview

Affected versions of this package are vulnerable to Uncaught Exception due to an error event thrown by busboy. An attacker can cause a full nodejs application to crash by sending a specially crafted multi-part upload request.

PoC

const express = require('express')
const multer  = require('multer')
const http  = require('http')
const upload = multer({ dest: 'uploads/' })
const port = 8888

const app = express()

app.post('/upload', upload.single('file'), function (req, res) {
  res.send({})
})

app.listen(port, () => {
  console.log(`Listening on port ${port}`)

  const boundary = 'AaB03x'
  const body = [
    '--' + boundary,
    'Content-Disposition: form-data; name="file"; filename="test.txt"',
    'Content-Type: text/plain',
    '',
    'test without end boundary'
  ].join('\r\n')
  const options = {
    hostname: 'localhost',
    port,
    path: '/upload',
    method: 'POST',
    headers: {
      'content-type': 'multipart/form-data; boundary=' + boundary,
      'content-length': body.length,
    }
  }
  const req = http.request(options, (res) => {
    console.log(res.statusCode)
  })
  req.on('error', (err) => {
    console.error(err)
  })
  req.write(body)
  req.end()
})

Remediation

Upgrade multer to version 2.0.0 or higher.

References

• GitHub Commit
• GitHub Issue

Overview

Affected versions of this package are vulnerable to Uncaught Exception due to improper handling of multipart requests. An attacker can cause the application to crash by sending a specially crafted malformed multi-part upload request that triggers an unhandled exception.

Remediation

Upgrade multer to version 2.0.2 or higher.

References

• GitHub Commit
• OpenJS Advisories
• Red Hat Bugzilla Bug

Overview

validator is a library of string validators and sanitizers.

Affected versions of this package are vulnerable to Incomplete Filtering of One or More Instances of Special Elements in the isLength() function that does not take into account Unicode variation selectors (\uFE0F, \uFE0E) appearing in a sequence which lead to improper string length calculation. This can lead to an application using isLength for input validation accepting strings significantly longer than intended, resulting in issues like data truncation in databases, buffer overflows in other system components, or denial-of-service.

PoC

Input;

const validator = require('validator');

console.log(`Is "test" (String.length: ${'test'.length}) length less than or equal to 3? ${validator.isLength('test', { max: 3 })}`);
console.log(`Is "test" (String.length: ${'test'.length}) length less than or equal to 4? ${validator.isLength('test', { max: 4 })}`);
console.log(`Is "test\uFE0F\uFE0F\uFE0F\uFE0F" (String.length: ${'test\uFE0F\uFE0F\uFE0F\uFE0F'.length}) length less than or equal to 4? ${validator.isLength('test\uFE0F\uFE0F\uFE0F', { max: 4 })}`);

Output:

Is "test" (String.length: 4) length less than or equal to 3? false
Is "test" (String.length: 4) length less than or equal to 4? true
Is "test️️️️" (String.length: 8) length less than or equal to 4? true

Remediation

Upgrade validator to version 13.15.22 or higher.

References

• GitHub Gist
• GitHub PR

Overview

ip is a Node library.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) via the isPublic function, by failing to identify hex-encoded 0x7f.1 as equivalent to the private addess 127.0.0.1. An attacker can expose sensitive information, interact with internal services, or exploit other vulnerabilities within the network by exploiting this vulnerability.

PoC

var ip = require('ip');

console.log(ip.isPublic("0x7f.1"));
//This returns true. It should be false because 0x7f.1 == 127.0.0.1 == 0177.1

Remediation

Upgrade ip to version 1.1.9, 2.0.1 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Issue
• GitHub PR
• Vulnerability Report
• Vulnerable Code

Overview

http-proxy-agent provides an http.Agent implementation that connects to a specified HTTP or HTTPS proxy server, and can be used with the built-in http module.

Affected versions of this package are vulnerable to Uninitialized Memory Exposure and Denial of Service (DoS) attacks due to passing unsanitized options to Buffer(arg).

Uninitialized memory Exposre PoC by ChALKer

// listen with: nc -l -p 8080

var url = require('url');
var https = require('https');
var HttpsProxyAgent = require('https-proxy-agent');

var proxy = {
  protocol: 'http:',
  host: "127.0.0.1",
  port: 8080
};

proxy.auth = 500; // a number as 'auth'
var opts = url.parse('https://example.com/');
var agent = new HttpsProxyAgent(proxy);
opts.agent = agent;
https.get(opts);

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 https-proxy-agent to version 2.1.0 or higher. Note This is vulnerable only for Node <=4

References

• HackerOne Report

Overview

https-proxy-agent provides an http.Agent implementation that connects to a specified HTTP or HTTPS proxy server, and can be used with the built-in https module.

Affected versions of this package are vulnerable to Uninitialized Memory Exposure and Denial of Service (DoS) attacks due to passing unsanitized options to Buffer(arg).

Note: CVE-2018-3739 is a duplicate of CVE-2018-3736.

Uninitialized memory Exposre PoC by ChALKer

// listen with: nc -l -p 8080

var url = require('url');
var https = require('https');
var HttpsProxyAgent = require('https-proxy-agent');

var proxy = {
  protocol: 'http:',
  host: "127.0.0.1",
  port: 8080
};

proxy.auth = 500; // a number as 'auth'
var opts = url.parse('https://example.com/');
var agent = new HttpsProxyAgent(proxy);
opts.agent = agent;
https.get(opts);

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 https-proxy-agent to version 2.2.0 or higher. Note This is vulnerable only for Node <=4

References

• HackerOne Report

Overview

bson is a BSON Parser for node and browser.

Affected versions of this package are vulnerable to Internal Property Tampering. The package will ignore an unknown value for an object's _bsotype, leading to cases where an object is serialized as a document rather than the intended BSON type.

NOTE: This vulnerability has also been identified as: CVE-2019-2391

Remediation

Upgrade bson to version 1.1.4 or higher.

References

• GitHub Commit
• Release Note

Overview

bson is a BSON Parser for node and browser.

Affected versions of this package are vulnerable to Internal Property Tampering. The package will ignore an unknown value for an object's _bsotype, leading to cases where an object is serialized as a document rather than the intended BSON type.

NOTE: This vulnerability has also been identified as: CVE-2020-7610

Remediation

Upgrade bson to version 1.1.4 or higher.

References

• GitHub Commit
• Release Note

Overview

mongoose is a Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.

Affected versions of this package are vulnerable to Prototype Pollution in document.js, via update functions such as findByIdAndUpdate(). This allows attackers to achieve remote code execution.

Note: Only applications using Express and EJS are vulnerable.

PoC

import { connect, model, Schema } from 'mongoose';

await connect('mongodb://127.0.0.1:27017/exploit');

const Example = model('Example', new Schema({ hello: String }));

const example = await new Example({ hello: 'world!' }).save();
await Example.findByIdAndUpdate(example._id, {
    $rename: {
        hello: '__proto__.polluted'
    }
});

// this is what causes the pollution
await Example.find();

const test = {};
console.log(test.polluted); // world!
console.log(Object.prototype); // [Object: null prototype] { polluted: 'world!' }

process.exit();

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:

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

• Application server

• Web server

• Web browser

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

Remediation

Upgrade mongoose to version 5.13.20, 6.11.3, 7.3.4 or higher.

References

• GitHub Commit
• GitHub Commit

Overview

Affected versions of this package are vulnerable to Remote Code Execution (RCE). This can occur when used with untrusted input, due to unsafe PAC file handling.

In order to exploit this vulnerability in practice, this either requires an attacker on your local network, a specific vulnerable configuration, or some second vulnerability that allows an attacker to set your config values.

NOTE: The fix for this vulnerability is applied in the node-degenerator library, a dependency is written by the same maintainer.

PoC

const pac = require('pac-resolver');

// Should keep running forever (if not vulnerable):
setInterval(() => {
    console.log("Still running");
}, 1000);

// Parsing a malicious PAC file unexpectedly executes unsandboxed code:
pac(`
    // Real PAC config:
    function FindProxyForURL(url, host) {
        return "DIRECT";
    }

    // But also run arbitrary code:
    var f = this.constructor.constructor(\`
        // Running outside the sandbox:
        console.log('Read env vars:', process.env);
        console.log('!!! PAC file is running arbitrary code !!!');
        console.log('Can read & could exfiltrate env vars ^');
        console.log('Can kill parsing process, like so:');
        process.exit(100); // Kill the vulnerable process
        // etc etc
    \`);

    f();

Remediation

Upgrade pac-resolver to version 5.0.0 or higher.

References

• GitHub Commit #1
• GitHub Commit #2
• Github Release
• Researcher Blog

Overview

ip is a Node library.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) via the ip.isPublic() and ip.isPrivate() functions. An attacker can interact with internal network resources by supplying specially crafted IP address such as octal localhost format ("017700000001") that is incorrectly identified as public.

Note:

This issue exists because of an incomplete fix for CVE-2024-29415.

PoC

Test octal localhost bypass:

node -e "const ip=require('ip'); console.log('017700000001 bypass:', ip.isPublic('017700000001'));" - returns true

Remediation

There is no fixed version for ip.

References

• GitHub Issue
• Security Report

Overview

ip is a Node library.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) via the ip.isPublic() and ip.isPrivate() functions. An attacker can interact with internal network resources by supplying specially crafted IP address such as null route ("0") that is being incorrectly identified as public.

Note: This issue exists because of an incomplete fix for CVE-2024-29415.

Exploit is only possible if the application and operating system interpret connection attempts to 0 or 0.0.0.0 as connections to 127.0.0.1.

PoC

Test null route bypass:

node -e "const ip=require('ip'); console.log('0 bypass:', ip.isPublic('0'));" - returns true

Remediation

There is no fixed version for ip.

References

• GitHub Issue
• Security Report

Overview

netmask is a library to parse IPv4 CIDR blocks.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF). It incorrectly evaluates individual IPv4 octets that contain octal strings as left-stripped integers, leading to an inordinate attack surface on hundreds of thousands of projects that rely on netmask to filter or evaluate IPv4 block ranges, both inbound and outbound.

For example, a remote unauthenticated attacker can request local resources using input data 0177.0.0.1 (127.0.0.1), which netmask evaluates as the public IP 177.0.0.1. Contrastingly, a remote authenticated or unauthenticated attacker can input the data 0127.0.0.01 (87.0.0.1) as localhost, yet the input data is a public IP and can potentially cause local and remote file inclusion (LFI/RFI). A remote authenticated or unauthenticated attacker can bypass packages that rely on netmask to filter IP address blocks to reach intranets, VPNs, containers, adjacent VPC instances, or LAN hosts, using input data such as 012.0.0.1 (10.0.0.1), which netmask evaluates as 12.0.0.1 (public).

NOTE: This vulnerability has also been identified as: CVE-2021-29418

Remediation

Upgrade netmask to version 2.0.1 or higher.

References

• GitHub Commit
• PoC
• Researcher Report
• Nuclei Templates

Overview

netmask is a library to parse IPv4 CIDR blocks.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF). It incorrectly evaluates individual IPv4 octets that contain octal strings as left-stripped integers, leading to an inordinate attack surface on hundreds of thousands of projects that rely on netmask to filter or evaluate IPv4 block ranges, both inbound and outbound.

For example, a remote unauthenticated attacker can request local resources using input data 0177.0.0.1 (127.0.0.1), which netmask evaluates as the public IP 177.0.0.1. Contrastingly, a remote authenticated or unauthenticated attacker can input the data 0127.0.0.01 (87.0.0.1) as localhost, yet the input data is a public IP and can potentially cause local and remote file inclusion (LFI/RFI). A remote authenticated or unauthenticated attacker can bypass packages that rely on netmask to filter IP address blocks to reach intranets, VPNs, containers, adjacent VPC instances, or LAN hosts, using input data such as 012.0.0.1 (10.0.0.1), which netmask evaluates as 12.0.0.1 (public).

NOTE: This vulnerability has also been identified as: CVE-2021-28918

Remediation

Upgrade netmask to version 2.0.1 or higher.

References

• GitHub Commit
• PoC
• Researcher Report

Overview

Affected versions of this package are vulnerable to Prototype Pollution via the mapValues() method, due to improper check in createObjectIterator function.

PoC

//when objects are parsed, all properties are created as own (the objects can come from outside sources (http requests/ file))
const hasOwn = JSON.parse('{"__proto__": {"isAdmin": true}}');

//does not have the property,  because it's inside object's own "__proto__"
console.log(hasOwn.isAdmin);

async.mapValues(hasOwn, (val, key, cb) => cb(null, val), (error, result) => {
  // after the method executes, hasOwn.__proto__ value (isAdmin: true) replaces the prototype of the newly created object, leading to potential exploits.
  console.log(result.isAdmin);
});

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:

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

• Application server

• Web server

• Web browser

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

Remediation

Upgrade async to version 2.6.4, 3.2.2 or higher.

References

• GitHub Backport PR
• GitHub Commit
• GitHub Commit
• PoC

Overview

bcrypt is an A library to help you hash passwords.

Affected versions of this package are vulnerable to Insecure Encryption. Data is truncated wrong when its length is greater than 255 bytes.

Remediation

Upgrade bcrypt to version 5.0.0 or higher.

References

• GitHub Issue
• GitHub PR 1
• GitHub PR 2

Overview

Affected versions of this package are vulnerable to Denial of Service (DoS). A malicious attacker can send a modified form to server, and crash the nodejs service. An attacker could sent the payload again and again so that the service continuously crashes.

PoC

await fetch('http://127.0.0.1:8000', { method: 'POST', headers: { ['content-type']: 'multipart/form-data; boundary=----WebKitFormBoundaryoo6vortfDzBsDiro', ['content-length']: '145', connection: 'keep-alive', }, body: '------WebKitFormBoundaryoo6vortfDzBsDiro\r\n Content-Disposition: form-data; name="bildbeschreibung"\r\n\r\n\r\n------WebKitFormBoundaryoo6vortfDzBsDiro--' });

Remediation

There is no fixed version for dicer.

References

• GitHub Commit
• GitHub Issue
• GitHub PR

Overview

mongodb is an official MongoDB driver for Node.js.

Affected versions of this package are vulnerable to Denial of Service (DoS). The package fails to properly catch an exception when a collection name is invalid and the DB does not exist, crashing the application.

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.

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 mongodb to version 3.1.13 or higher.

References

• NPM Security Advisory

Overview

mquery is an Expressive query building for MongoDB

Affected versions of this package are vulnerable to Prototype Pollution via the mergeClone() function.

PoC by zhou, peng

mquery = require('mquery');
var malicious_payload = '{"__proto__":{"polluted":"HACKED"}}';
console.log('Before:', {}.polluted); // undefined
mquery.utils.mergeClone({}, JSON.parse(malicious_payload));
console.log('After:', {}.polluted); // HACKED

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:

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

• Application server

• Web server

• Web browser

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

Remediation

Upgrade mquery to version 3.2.5 or higher.

References

• GitHub Commit
• GitHub PR

Overview

semver is a semantic version parser used by npm.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via the function new Range, when untrusted user data is provided as a range.

PoC

const semver = require('semver')
const lengths_2 = [2000, 4000, 8000, 16000, 32000, 64000, 128000]

console.log("n[+] Valid range - Test payloads")
for (let i = 0; i =1.2.3' + ' '.repeat(lengths_2[i]) + '<1.3.0';
const start = Date.now()
semver.validRange(value)
// semver.minVersion(value)
// semver.maxSatisfying(["1.2.3"], value)
// semver.minSatisfying(["1.2.3"], value)
// new semver.Range(value, {})

const end = Date.now();
console.log('length=%d, time=%d ms', value.length, end - start);
}

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.

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 5.7.2, 6.3.1, 7.5.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit
• GitHub PR
• Vulnerable Code
• Vulnerable Code
• Vulnerable Code

Overview

mquery is an Expressive query building for MongoDB

Affected versions of this package are vulnerable to Prototype Pollution via the merge function within lib/utils.js. Depending on if user input is provided, an attacker can overwrite and pollute the object prototype of a program.

PoC

   require('./env').getCollection(function(err, collection) {
      assert.ifError(err);
      col = collection;
      done();
    });
    var payload = JSON.parse('{"__proto__": {"polluted": "vulnerable"}}');
    var m = mquery(payload);
    console.log({}.polluted);
// The empty object {} will have a property called polluted which will print vulnerable

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:

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

• Application server

• Web server

• Web browser

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

Remediation

Upgrade mquery to version 3.2.3 or higher.

References

• mquery GitHub Commit
• rxdb GitHub Commit

Overview

lodash.template is a The Lodash method _.template exported as a Node.js module.

Affected versions of this package are vulnerable to Code Injection via template.

PoC

var _ = require('lodash');

_.template('', { variable: '){console.log(process.env)}; with(obj' })()

Remediation

There is no fixed version for lodash.template.

References

• GitHub Commit
• Vulnerable Code

Overview

mongoose is a Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.

Affected versions of this package are vulnerable to Prototype Pollution in the Schema.path() function.

Note: CVE-2022-24304 is a duplicate of CVE-2022-2564.

PoC:

const mongoose = require('mongoose');
const schema = new mongoose.Schema();

malicious_payload = '__proto__.toString'

schema.path(malicious_payload, [String])

x = {}
console.log(x.toString())

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:

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

• Application server

• Web server

• Web browser

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

Remediation

Upgrade mongoose to version 5.13.15, 6.4.6 or higher.

References

• Github Commit
• GitHub Commit
• GitHub Issue