Prototype pollution in pathval

[Asjidkalam]

✍️ Description

pathval is chaijs's package to retrieve Object value using a string path, this package is vulnerable to Prototype Pollution via the setPathValue function.

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.

🕵️‍♂️ Proof of Concept

Install the package(npm i pathval), run the below code:

var pathval = require('pathval');

var obj = {};
console.log("Before:" + obj.polluted);
pathval.setPathValue(obj, '__proto__.polluted', 'pwned!');
console.log("After:" + polluted);

Outputs pwned!.

💥 Impact

It leads to either denial of service by triggering JavaScript exceptions or tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

✅ Checklist

• Created and populated the README.md and vulnerability.json files
• Provided the repository URL and any applicable permalinks
• Defined all the applicable weaknesses (CWEs)
• Proposed the CVSS vector items i.e. User Interaction, Attack Complexity
• Checked that the vulnerability affects the latest version of the package released
• Checked that a fix does not currently exist that remediates this vulnerability
• Complied with all applicable laws

[Mik317]

LGTM 😄 🍰

Cheers,
Mik

[mufeedvh]

Good finding! 👏🔥

[bbeale]

Nice find 👍

[ghost]

It looks like there's already a fix in the works for this one so gonna close it off - chaijs/pathval#58

Thanks for the disclosure though!