Security Fix for Prototype Pollution - huntr.dev

https://huntr.dev/users/d3m0n-r00t has fixed the Prototype Pollution vulnerability 🔨. Think you could fix a vulnerability like this?

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📊 Metadata *

Fixed Prototype Pollution in properties

Bounty URL: https://www.huntr.dev/bounties/1-npm-properties-reader

⚙️ Description *

properties-reader is vulnerable to Prototype Pollution. 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 src 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) *

// poc.js
var propertiesReader = require('properties-reader');
console.log("Before : " + {}.polluted)
console.log("Before : " + {}.polluted1)
var properties = propertiesReader('./payload.ini');
properties.set("__proto__.polluted1", "Yes! Its Polluted1");
console.log("After : " + {}.polluted)
console.log("After : " + {}.polluted1)

//payload.ini
[__proto__]
polluted = "Yes! Its Polluted"

npm i properties-reader # Install affected module
node poc.js #  Run the PoC

propertiespoc

🔥 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. propertiespof

👍 User Acceptance Testing (UAT)

All ok.

steveukx / properties