# Exploiting Insecure Deserialization

> Use when identifying and exploiting insecure deserialization vulnerabilities in Java, PHP, Python, and .NET applications to achieve remote code execution during authorized penetration tests. Use when working with exploiting insecure deserialization.

- Skill: `oyi77/exploiting-insecure-deserialization` (Agent Skill)
- Install (CLI): `npx skillmds add oyi77/exploiting-insecure-deserialization`
- Raw SKILL.md: https://api.skillmd.com/api/skills/oyi77/exploiting-insecure-deserialization/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: Apache-2.0
- Author: oyi77 (https://skillmd.com/u/oyi77)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/oyi77/exploiting-insecure-deserialization

---


# Exploiting Insecure Deserialization

## Overview

Cybersecurity skill for exploiting insecure deserialization. Follows industry best practices and security standards.

## When to Use
**Trigger phrases:**
- "exploiting insecure deserialization"
- "Identifying and exploiting insecure deserialization vulnerabilities in Java, PHP"


- During authorized penetration tests when applications process serialized data (cookies, API parameters, message queues)
- When identifying Java serialization markers (`ac ed 00 05` / `rO0AB`) in HTTP traffic
- For testing PHP applications that use `unserialize()` on user-controlled input
- When evaluating .NET applications using `BinaryFormatter`, `ObjectStateFormatter`, or `ViewState`
- During security assessments of applications using pickle (Python), Marshal (Ruby), or YAML deserialization


## 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

- **Authorization**: Written penetration testing agreement with RCE testing scope
- **ysoserial**: Java deserialization exploit tool (`git clone https://github.com/frohoff/ysoserial.git`)
- **ysoserial.net**: .NET deserialization exploit tool (`git clone https://github.com/pwntester/ysoserial.net.git`)
- **PHPGGC**: PHP deserialization gadget chain generator (`git clone https://github.com/ambionics/phpggc.git`)
- **Burp Suite Professional**: With Java Deserialization Scanner extension
- **Java Runtime**: For running ysoserial
- **Collaborator/interactsh**: For out-of-band confirmation of code execution

## 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 insecure deserialization. Identify attack surface.
2. **Vulnerability Identification** — Enumerate potential insecure deserialization weaknesses using automated and manual techniques.
3. **Exploit Development/Selection** — Choose or develop exploits targeting identified insecure deserialization vulnerabilities.
4. **Execution** — Execute the insecure deserialization 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 insecure deserialization 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. |