Overview
Prototype pollution vulnerability in 'nestie' versions 0.0.0 through 1.0.0 allows attacker to cause a denial of service and may lead to remote code execution.
Details
The NPM module `nestie` can be abused by Prototype Pollution vulnerability since the function `nestie()` does not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution.
PoC Details
The `nestie()` function accepts `input, glue` as argument. Due to the absence of validation on the values passed into the `input` argument, an attacker can supply a malicious value by adjusting the value to include the `__proto__` property. Since there is no validation before assigning the property here to check whether the assigned argument is the Object's own property or not, the property `polluted` will be directly be assigned to the new object thereby polluting the Object prototype. Later in the code, if there is a check to validate `polluted` the valued would be substituted as "Yes! Its Polluted" as it had been polluted.
PoC Code
var { nestie } = require("nestie")
console.log("Before : " + {}.polluted);
nestie({"__proto__.polluted": "Yes! Its Polluted"})
console.log("After : " + {}.polluted);
Affected Environments
0.0.0 to 1.0.0
Prevention
Upgrade to version 1.0.1