Fixed Prototype pollution in ptree

[Asjidkalam]

📊 Metadata *

Prototype Pollution bug

Bounty URL: https://www.huntr.dev/bounties/1-npm-%40dotvirus%2Fptree/

⚙️ Description *

@dotvirus/ptree is vulnerable to Prototype Pollution. This package allowing for modification of prototype behavior, which may result in Information Disclosure/DoS/RCE.

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.

💻 Technical Description *

The bug is fixed by validating the input segments to check for prototypes. It is implemented by a simple validation to check for prototype keywords (__proto__, constructor and prototype), where if it exists, the function returns the object without modifying it, thus fixing the Prototype Pollution Vulnerability.

🐛 Proof of Concept (PoC) *

Clone the project, install the required dependencies and on running the below snippet of code, it triggers prototype pollution and logs true.

// poc.js
const ptree = require('@dotvirus/ptree').default

console.log('Before: ' + {}.polluted)
const tree = new ptree({})
tree.set('__proto__.polluted', true)
console.log('After: ' + {}.polluted)

🔥 Proof of Fix (PoF) *

After the fix is applied, it returns undefined since the polluted referred in the PoC is no more accessible(which is intended). Hence fixing the issue.

👍 User Acceptance Testing (UAT)

Tests run, all ok.
Just prevented some keywords as keys and no breaking changes are introduced. :)

[huntr-helper]

👋 Hello, @dotvirus - @Asjidkalam has opened a PR to us with a fix for a potential vulnerability in your repository. To view the vulnerability, please refer to the bounty URL in the first comment, above.

Ultimately, you get to decide if the fix is 👍 or 👎. If you are happy with the fix, please write a new comment (@huntr-helper - LGTM) and we will open a PR to your repository with the fix. All remaining PRs for this vulnerability will be automatically closed.

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@dotvirus & @Asjidkalam - thank you for your efforts in securing the world’s open source code! 🎉