Exploiting Prototype Pollution In Javascript

---
name: exploiting-prototype-pollution-in-javascript
description: Use when detect and exploit JavaScript prototype pollution vulnerabilities
  on both client-side and server-side applications to achieve XSS, RCE, and authentication
  bypass through property injection. Use when detecting and exploit javascript prototype
  pollution vulnerabilities on both client-side.
domain: cybersecurity
tags:
- prototype-pollution
- javascript
- node-js
- xss
- rce
- property-injection
- dom-xss
- server-side-pollution
subdomain: web-application-security
version: '1.0'
author: oyi77
license: Apache-2.0
nist_csf:
- PR.PS-01
- ID.RA-01
- PR.DS-10
- DE.CM-01
category: cybersecurity
---

# Exploiting Prototype Pollution In Javascript

## Overview

Cybersecurity skill for exploiting prototype pollution in javascript. Follows industry best practices and security standards.

## When to Use
**Trigger phrases:**
- "exploiting prototype pollution in javascript"
- "Detect and exploit JavaScript prototype pollution vulnerabilities on both client"

- When testing Node.js or JavaScript-heavy web applications
- During assessment of APIs accepting deep-merged JSON objects
- When testing client-side JavaScript frameworks for DOM XSS via prototype pollution
- During code review of object merge/clone/extend operations
- When evaluating npm packages for prototype pollution gadgets


## When NOT to Use

- When you lack proper authorization for testing
- For production systems without change management
- When the task requires legal or compliance expertise beyond technical scope


## Prerequisites
- Burp Suite with DOM Invader extension for client-side prototype pollution detection
- Node.js development environment for server-side testing
- Understanding of JavaScript prototype chain and object inheritance
- Knowledge of common pollution gadgets (sources, sinks, and exploitable properties)
- Prototype Pollution Gadgets Scanner Burp extension for server-side detection
- Browser developer console for client-side prototype manipulation


> **Legal Notice:** This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws.

## Workflow

```python
# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}
```

1. **Reconnaissance** — Gather information about the target related to prototype pollution in javascript. Identify attack surface.
2. **Vulnerability Identification** — Enumerate potential prototype pollution in javascript weaknesses using automated and manual techniques.
3. **Exploit Development/Selection** — Choose or develop exploits targeting identified prototype pollution in javascript vulnerabilities.
4. **Execution** — Execute the prototype pollution in javascript test in a controlled manner with proper authorization.
5. **Post-Exploitation** — Document the impact and extent of successful exploitation.
6. **Reporting** — Write detailed findings with reproduction steps, impact assessment, and remediation guidance.

## Tools

- **Vulnerability Scanner** — Automated weakness identification
- **Exploitation Framework** — Controlled exploitation testing
- **Reporting Tool** — Findings documentation and tracking


## Process

1. **Reconnaissance** — Gather target information, identify attack surface, enumerate services
1. **Analysis/Exploitation** — Execute the technique, analyze results, document findings
1. **Reporting** — Document IOCs, write findings, provide remediation recommendations

## Verification

- [ ] All prototype pollution in javascript procedures executed completely and documented
- [ ] Findings validated against multiple data sources
- [ ] False positives identified and filtered
- [ ] Results documented with evidence and timestamps
- [ ] Recommendations provided with risk-based prioritization

## Anti-Rationalization Table

| Rationalization | Reality |
|---|---|
| "We are too small to be targeted" | Automated attacks target everyone. Size does not matter. |
| "Security slows us down" | A breach slows you down 100x more. Build security in from the start. |
| "We will fix it after launch" | Vulnerabilities in production are exploited within hours. Fix before deploy. |