# Deserialization Insecure

Insecure deserialization playbook.

- Repository: https://github.com/yaklang/hack-skills (2601 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-09-13
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add yaklang/hack-skills --skill deserialization-insecure -g -a claude-code -y`
Codex: `npx skills add yaklang/hack-skills --skill deserialization-insecure -g -a codex -y`
Cursor: `npx skills add yaklang/hack-skills --skill deserialization-insecure -g -a cursor -y`
Gemini CLI: `npx skills add yaklang/hack-skills --skill deserialization-insecure -g -a gemini-cli -y`

## Description

Insecure deserialization playbook. Use when Java, PHP, or Python applications deserialize untrusted data via ObjectInputStream, unserialize, pickle, or similar mechanisms that may lead to RCE, file access, or privilege escalation.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# SKILL: Insecure Deserialization, Expert Attack Playbook

> **AI LOAD INSTRUCTION**: Expert deserialization techniques across Java, PHP, and Python. Covers gadget chain selection, traffic fingerprinting, tool usage (ysoserial, PHPGGC), Shiro/WebLogic/Commons Collections specifics, Phar deserialization, and Python pickle abuse. Base models often miss the distinction between finding the sink and finding a usable gadget chain.

## 0. RELATED ROUTING

- [jndi-injection](../jndi-injection/SKILL.md) when deserialization leads to JNDI lookup (e.g., post-JDK 8u191 bypass via LDAP → deserialization)
- [unauthorized-access-common-services](../unauthorized-access-common-services/SKILL.md) when the deserialization endpoint is an exposed management service (RMI Registry, T3, AJP)
- [ghost-bits-cast-attack](../ghost-bits-cast-attack/SKILL.md) when a WAF blocks your BCEL ClassLoader or Fastjson `@type` payload, Ghost Bits wraps each bytecode byte in a Unicode char whose low 8 bits match, yielding a payload the WAF cannot fingerprint

### Advanced Reference

Also load [JAVA_GADGET_CHAINS.md](./JAVA_GADGET_CHAINS.md) when you need:
- Java gadget chain version compatibility matrix (CommonsCollections 1, 7, CommonsBeanutils, Spring, JDK-only, Groovy, Hibernate, ROME, C3P0, etc.)
- SnakeYAML gadget (ScriptEngineManager/URLClassLoader) with exploit JAR structure
- Hessian/Kryo/Avro/XStream deserialization patterns and traffic fingerprints
- .NET ViewState deserialization (machineKey requirement, ViewState forgery with ysoserial.net, Blacklist3r)
- Ruby YAML.load vs YAML.safe_load exploitation with version-specific chains
- Detection fingerprints: magic bytes table by format (Java `AC ED`, .NET `AAEAAD`, Python pickle `80 0N`, PHP `O:`, Ruby `04 08`)

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## 1. TRAFFIC FINGERPRINTING, IS IT DESERIALIZATION?

### Java Serialized Objects

The rest: https://github.com/yaklang/hack-skills/blob/HEAD/skills/deserialization-insecure/SKILL.md