Security fix for prototype pollution

[arjunshibu]

📊 Metadata *

convict 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-convict

⚙️ 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 *

Fix implemented by not allowing to modify object prototype.

🐛 Proof of Concept (PoC) *

• Create the following PoC file:

// poc.js
var convict = require("convict");
var obj = {};
var config = convict(obj);
console.log("Before : " + {}.polluted);
config.set("__proto__.polluted","Yes! Its Polluted");
console.log("After : " + {}.polluted);

• Execute the following commands in another terminal:

npm i convict # Install affected module
node poc.js #  Run the PoC

• Check the Output:

Before : undefined
After : Yes! Its Polluted

🔥 Proof of Fix (PoF) *

Prototype pollution is fixed as seen below.

👍 User Acceptance Testing (UAT)

• I've executed unit tests.
• After fix the functionality is unaffected.

[JamieSlome]

@madarche - it would be good to get your thoughts here, thanks! 🍰

We also have proposed:

#2 & #3

[Mik317]

LGTM 😄 🍰

Cheers,
Mik

[mzfr]

Looks good 👍

[huntr-helper]

Congratulations arjunshibu - your fix has been selected! 🎉

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