How do I install the Web Deserialization skill?

Run npx skillmds@latest add noorqureshi/web-deserialization in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Web Deserialization safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Web Deserialization?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Web Deserialization free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Web Deserialization?

NoorQureshi (@noorqureshi) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Web Deserialization by noorqureshi — Agent Skill

Name: Web Deserialization
Author: NoorQureshi

Web Deserialization

Insecure deserialization → RCE via gadget chains. Load when the app deserializes attacker data: Java (rO0/AC ED base64), PHP `unserialize` (O:), Python pickle, .NET BinaryFormatter/ViewState, Ruby Marshal/YAML. Signals: serialized blobs in cookies/params, `__VIEWSTATE`, `rO0AB`, `O:8:`.

NoorQureshi c9c4065 2 files · 5.6 KB Updated Sep 17, 2026

File contents

Insecure deserialization

When it applies

The app takes serialized objects from the client (cookies, hidden fields, params, message queues) and deserializes them. Recognizable by format markers.

Why it works

Deserialization reconstructs objects and can invoke their methods (magic methods, readObject, __wakeup). A crafted object graph ("gadget chain") strings together existing library methods to reach a dangerous sink — command execution — during/after deserialization.

Method

Payloads & full variation set: cheatsheet.md next to this file — work the set, not the first line.

Spot the blob & format: Java rO0AB/AC ED 00 05, PHP O:8:"...":, .NET __VIEWSTATE/AAEAAAD, Python pickle, Ruby Marshal \x04\x08.
Confirm it's deserialized untrusted: tamper a byte → parse error/behaviour change.
Generate a gadget chain with the right tool for a library on the classpath:
- Java: ysoserial CommonsCollections1 'curl <collab>' | base64
- PHP: phpggc Monolog/RCE1 system id (pick a gadget matching a loaded framework)
- .NET: ysoserial.net (ViewState needs the MAC key or MAC-disabled).
Deliver in the sink; start with an OOB command (curl/nslookup to your host) as safe proof.

Gotchas

The chain must match a library actually present (Commons-Collections version, Monolog, etc.) — enumerate dependencies.
Java: prefer a DNS/OOB gadget to confirm before an RCE payload.
.NET ViewState needs the machineKey unless MAC validation is off — check for leaked web.config.

Verify success

An OOB callback or command output proving code executed during deserialization.

References

ysoserial / phpggc / ysoserial.net; PortSwigger deserialization labs; OWASP.

---name: web-deserializationdescription: Insecure deserialization → RCE via gadget chains. Load when the app deserializes attacker data: Java (rO0/AC ED base64), PHP `unserialize` (O:), Python pickle, .NET BinaryFormatter/ViewState, Ruby Marshal/YAML. Signals: serialized blobs in cookies/params, `__VIEWSTATE`, `rO0AB`, `O:8:`.---# Insecure deserialization## When it appliesThe app takes serialized objects from the client (cookies, hidden fields, params, messagequeues) and deserializes them. Recognizable by format markers.## Why it worksDeserialization reconstructs objects and can invoke their methods (magic methods, readObject,`__wakeup`). A crafted object graph ("gadget chain") strings together existing library methodsto reach a dangerous sink — command execution — during/after deserialization.## Method> **Payloads & full variation set:** [`cheatsheet.md`](cheatsheet.md) next to this file — work the set, not the first line.1. **Spot the blob & format**: Java `rO0AB`/`AC ED 00 05`, PHP `O:8:"...":`, .NET `__VIEWSTATE`/`AAEAAAD`, Python pickle, Ruby Marshal `\x04\x08`.2. **Confirm it's deserialized untrusted**: tamper a byte → parse error/behaviour change.3. **Generate a gadget chain** with the right tool for a library on the classpath: - Java: `ysoserial CommonsCollections1 'curl <collab>' | base64` - PHP: `phpggc Monolog/RCE1 system id` (pick a gadget matching a loaded framework) - .NET: `ysoserial.net` (ViewState needs the MAC key or MAC-disabled).4. **Deliver** in the sink; start with an OOB command (`curl`/`nslookup` to your host) as safe proof.## Gotchas- The chain must match a library actually present (Commons-Collections version, Monolog, etc.) — enumerate dependencies.- Java: prefer a DNS/OOB gadget to confirm before an RCE payload.- .NET ViewState needs the machineKey unless MAC validation is off — check for leaked web.config.## Verify successAn OOB callback or command output proving code executed during deserialization.## Referencesysoserial / phpggc / ysoserial.net; PortSwigger deserialization labs; OWASP.

Frequently asked questions