Offensive Deserialization

Q: What is a Claude Code skill and how does the Offensive Deserialization skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Offensive Deserialization is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Security · Sub-category: web-security · Last updated: 2026-09-28

lang:javascript lang:php

Insecure deserialization exploitation across Java, PHP, .NET, Python, Node.js, and Ruby. Covers gadget chain construction with ysoserial/phpggc/ysoserial.net, ObjectInputStream and BinaryFormatter sink identification, pickle __reduce__ RCE, phar:// wrapper abuse, Jackson polymorphic typing, Json.NET TypeNameHandling, ViewState tampering, node-serialize IIFE injection, Ruby Marshal.load and YAML.load gadgets, framework-specific chains for Spring/Hibernate/Laravel/Symfony, modern attack surfaces including Kubernetes admission webhooks and message queue consumers, WAF bypass through encoding layers and content-type manipulation, and serialVersionUID/JMX/RMI vectors. Activate when the engagement involves deserialization sinks, serialized data in cookies or request bodies, gadget chain development, magic method abuse, ysoserial payload generation, or any review of marshalling and unmarshalling logic in target applications.

Security BStatic scan: minor findingsHow grading works ›

From the source SKILL.md

Deserialization vulnerabilities arise when an application reconstructs objects from serialized byte streams without validating the type, integrity, or origin of the data. Object reconstruction triggers constructors, finalizers, and language-specific magic methods, so an attacker who controls the serialized input often achieves remote code execution before any application-level validation runs.

What this skill does

Offensive Deserialization is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/offensive-deserialization/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Offensive Deserialization Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 201,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/offensive-deserialization
curl -L https://claudskills.com/skills/offensive-deserialization/SKILL.md \
  -o ~/.claude/skills/offensive-deserialization/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/offensive-deserialization/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/offensive-deserialization/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\offensive-deserialization\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Offensive Deserialization Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/offensive-deserialization/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Offensive Deserialization skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Offensive Deserialization skill?

Use Offensive Deserialization when your Claude Code task falls under the Security category — specifically in the web security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Offensive Deserialization" or describe the task and let Claude pick). Browse related skills at /category/security/.

What is a Claude Code skill and how does the Offensive Deserialization skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Offensive Deserialization is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/SnailSploit/claude-red/blob/HEAD/Skills/web/offensive-deserialization/SKILL.md
License: MIT
Author: SnailSploit

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

SnailSploit. (2026). Offensive Deserialization [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/offensive-deserialization/

BibTeX

@misc{offensive-deserialization-2026,
  author    = {SnailSploit},
  title     = {Offensive Deserialization [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/offensive-deserialization/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/offensive-deserialization.svg)](https://claudskills.com/skills/offensive-deserialization/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade B · scanned 2026-10-04 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 5 of 10 categories (execution, filesystem, hidden-helper, obfuscation, supply-chain), including a high-severity pattern. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

✓ Prompt injection
✓ Data exfiltration
⚠ Supply chain
✓ Reverse shell
✓ Credentials
⚠ Execution
⚠ Filesystem
✓ Persistence
⚠ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: B](https://img.shields.io/badge/Security-B-558b2f)](https://claudskills.com/skills/offensive-deserialization/#security)

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Browse all Security skills → Top 100 skills

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