Prototype Pollution to Remote Code Execution (RCE) Exploitation

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URL:

https://lnkd.in/eYGBNBab

You Should Know:

Prototype Pollution is a vulnerability that occurs when an attacker can inject properties into existing JavaScript prototype objects, leading to unexpected behavior in the application. This can escalate to Remote Code Execution (RCE), allowing attackers to execute arbitrary code on the target system. Below are some practical steps, commands, and code snippets to understand and mitigate this vulnerability.

Understanding Prototype Pollution

1. Identify Vulnerable Code:

Look for JavaScript code that merges or extends objects without proper validation. For example: 

function merge(target, source) {
for (let key in source) {
if (source.hasOwnProperty(key)) {
target[key] = source[key];
}
}
return target;
}

This code is vulnerable if an attacker controls the `source` object.

2. Exploitation Example:

An attacker can pollute the prototype by injecting malicious properties: 

let maliciousPayload = JSON.parse('{"<strong>proto</strong>":{"isAdmin":true}}');
merge({}, maliciousPayload);

This modifies the prototype of all objects, granting unintended privileges.

3. Mitigation Steps:

  • Use libraries like `lodash` with built-in safeguards.
  • Validate and sanitize input objects.
  • Freeze the prototype using Object.freeze(Object.prototype).

Commands for Testing and Mitigation

  • Node.js Debugging:
    Use `node inspect