Payloads Mass Assignment

---
name: payloads-mass-assignment
description: "A mass assignment attack is a security vulnerability that occurs when a web application automatically assigns user-supplied input values to properties or variables of a program object. This can become an issue if a user is able to modify attributes they should not have access to, like a user's permissions or an admin flag. Mass assignment vulnerabilities are most common in web applications that..."
---

# Mass Assignment Payloads

> **Source:** [PayloadsAllTheThings/Mass Assignment](https://github.com/swisskyrepo/payloadsallthethings/tree/master/Mass%20Assignment)
> **Category:** `payloads-web` | **Skill ID:** `payloads-mass-assignment`

## Overview

Mass assignment attack payloads for unauthorized parameter binding in web frameworks.

This skill integrates the full **PayloadsAllTheThings** (PATT) payload library for the **Mass Assignment Payloads** domain into the REA_Skill framework. Use it during authorized penetration testing, bug bounty research, security audits, and CTF challenges.

## Workflow

### 1. Recon & Identification
- Identify the target technology stack and injection points
- Enumerate endpoints, parameters, and input vectors
- Determine applicable payload categories from the reference below

### 2. Payload Selection
- Browse the PATT payload library for the attack class
- Select encoding-appropriate payloads for the target environment
- Consider WAF bypass variants and obfuscation techniques

### 3. Exploitation (Authorized Only)
- Test payloads in order: passive → active → escalation
- Document every payload tested and its response
- Capture PoC evidence (screenshots, HTTP logs, curl output)

### 4. Verification & Reporting
- Confirm the vulnerability with a clean minimal PoC
- Map findings to CVE/CWE where applicable
- Report with remediation recommendations and code fixes

---

## Full PATT Reference

# Mass Assignment

> A mass assignment attack is a security vulnerability that occurs when a web application automatically assigns user-supplied input values to properties or variables of a program object. This can become an issue if a user is able to modify attributes they should not have access to, like a user's permissions or an admin flag.

## Summary

* [Methodology](#methodology)
* [Labs](#labs)
* [References](#references)

## Methodology

Mass assignment vulnerabilities are most common in web applications that use Object-Relational Mapping (ORM) techniques or functions to map user input to object properties, where properties can be updated all at once instead of individually. Many popular web development frameworks such as Ruby on Rails, Django, and Laravel (PHP) offer this functionality.

For instance, consider a web application that uses an ORM and has a user object with the attributes `username`, `email`, `password`, and `isAdmin`. In a normal scenario, a user might be able to update their own username, email, and password through a form, which the server then assigns to the user object.

However, an attacker may attempt to add an `isAdmin` parameter to the incoming data like so:

```json
{
    "username": "attacker",
    "email": "attacker@email.com",
    "password": "unsafe_password",
    "isAdmin": true
}
```

If the web application is not checking which parameters are allowed to be updated in this way, it might set the `isAdmin` attribute based on the user-supplied input, giving the attacker admin privileges

## Labs

* [PentesterAcademy - Mass Assignment I](https://attackdefense.pentesteracademy.com/challengedetailsnoauth?cid=1964)
* [PentesterAcademy - Mass Assignment II](https://attackdefense.pentesteracademy.com/challengedetailsnoauth?cid=1922)
* [Root Me - API - Mass Assignment](https://www.root-me.org/en/Challenges/Web-Server/API-Mass-Assignment)

## References

* [Mass Assignment Cheat Sheet - OWASP - March 15, 2021](https://web.archive.org/web/20260216020815/https://cheatsheetseries.owasp.org/cheatsheets/Mass_Assignment_Cheat_Sheet.html)
* [What is Mass Assignment? Attacks and Security Tips - Yoan MONTOYA - June 15, 2023](https://www.vaadata.com/blog/what-is-mass-assignment-attacks-and-security-tips/)

---

## REA MCP Integration

```javascript
// REA MCP — Automated payload injection via REA tools
// Use analyze_function, procedure_pseudo_code, or observe_native_calls
// to identify injection sinks, then apply payloads from this skill.
```

## Legal Notice

> ⚠️ **Authorized Use Only.** All payloads in this skill are for security research, penetration testing with written permission, CTF competitions, and defensive study. Unauthorized use against systems you do not own or have explicit permission to test is illegal.