JavaScript

Multiple obfuscation techniques can be deobfuscated using de4js, or JavaScript Deobfuscator.

Deobfuscating Obfuscator.io can be done using Obfuscator.io Deobfuscator.

If there’s access to package-lock.json, a check for vulnerable packages can be done by running the command npm audit in the same directory as package-lock.json.

# npm audit report

ion-parser  *
Severity: critical
ion-parser Prototype Pollution when malicious INI file submitted to application that parses with `parse` - https://github.com/advisories/GHSA-7vrv-5m2h-rjw9
fix available via `npm audit fix`
node_modules/ion-parser

1 critical severity vulnerability

Other tools like Snyk CLI can be used to achieve the same results.

Prototype pollution is a vulnerability that allows an attacker to modify the prototype of an object and potentially execute arbitrary code.

For example, consider the following code:

const merge = require('deepmerge');

let obj = {};
let payload = '{"__proto__": {"polluted": true}}';

let result = merge(obj, JSON.parse(payload));

console.log(obj.polluted); // true

In this example, the merge function merges the obj object with the payload object. The payload object has a property __proto__ that modifies the prototype of the obj object. As a result, the obj object now has a polluted property.