Security Fix for Prototype Pollution

[ready-research]

📊 Metadata *

set-deep-prop is vulnerable to Prototype Pollution.
This package allowing for modification of prototype behavior, which may result in Information Disclosure/DoS/RCE.

Bounty URL: https://www.huntr.dev/bounties/1-npm-set-deep-prop/

⚙️ Description *

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.

💻 Technical Description *

Fixed by avoiding setting magical attributes.

🐛 Proof of Concept (PoC) *

1. Create the following PoC file:

// poc.js
const setDeepProp = require('set-deep-prop');
var obj = {};
console.log("Before : " + {}.polluted);
setDeepProp(obj, ["__proto__","polluted"], "Yes! Its Polluted");
console.log("After : " + {}.polluted);

2. Execute the following commands in terminal:

npm i set-deep-prop # Install affected module
node poc.js #  Run the PoC

3. Check the Output:

Before : undefined
After : Yes! Its Polluted

🔥 Proof of Fix (PoF) *

After fix execution will block prototype pollution and polluted will be [undefined.]

👍 User Acceptance Testing (UAT)

After fix functionality is unaffected.

[huntr-helper]

👋 Hello, @mmckelvy. @ready-research 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. If you want this fix in your repository, a PR will automatically open once you comment:

@huntr-helper - LGTM

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