offensive-deserialization

offensive-deserialization is a skill for Claude Code, Codex from SnailSploit/Claude-Red. It costs 189 tokens per session (5,748 once invoked), scanned A, original, MIT.

A security-testing guide for insecure deserialization, a flaw where an application rebuilds program objects from untrusted stored or transmitted data.

In plain words
What is it for?
Use it during authorized tests of serialized cookies, requests, uploads, message queues, and framework-specific object formats across several programming languages.
Why use it?
It helps testers find input paths where this process may allow unintended actions, including running code on the server.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it during authorized tests of serialized cookies, requests, uploads, message queues, and framework-specific object formats across several programming languages.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/snailsploit/claude-red/offensive-deserialization
About the project

claude-red is a library of structured skills that give Claude specialized offensive-security methods for areas such as web vulnerabilities, shellcode, exploit development, and identity systems. It is intended for authorized red-team work, bug-bounty triage, security research, CTF preparation, and operator training. Its catalogue contains the project's skills for loading these security specializations into Claude.

SnailSploit/Claude-Red · 7,620 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add SnailSploit/Claude-Red --skill offensive-deserialization
Clone the repo
git clone --depth 1 https://github.com/SnailSploit/Claude-Red

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for offensive-deserialization

README.md
[![agentmods](https://agentmods.dev/badge/skills/snailsploit/claude-red/offensive-deserialization/github.svg)](https://agentmods.dev/skills/snailsploit/claude-red/offensive-deserialization)
Your own site
<a href="https://agentmods.dev/skills/snailsploit/claude-red/offensive-deserialization"><img src="https://agentmods.dev/badge/skills/snailsploit/claude-red/offensive-deserialization/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for offensive-deserialization

Your own site · 80×15
<a href="https://agentmods.dev/skills/snailsploit/claude-red/offensive-deserialization"><img src="https://agentmods.dev/badge/skills/snailsploit/claude-red/offensive-deserialization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 189 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,748 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. ✓ AI security review Sonnet 5 · 6 Sept 2026 📄 Read the review Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 4 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high YARA Match · line 120
    YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).
    Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
  • high Supply Chain · line 172
    Remote code is downloaded and executed. This bypasses code review and could introduce malicious code.
    Fix: Avoid downloading and executing remote scripts. Use trusted packages from PyPI/npm. If remote fetch is required, verify checksums and use HTTPS.
  • high Privilege Escalation · line 169
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • medium Rogue Agent · line 110
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00189 $0.05748
Opus 5.5 $0.00076 $0.02299
Sonnet 5.5 $0.00038 $0.01150
Haiku 4.5 $0.00019 $0.00575

Measured 1mo ago against content hash 2dfb6f4dfa3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

offensive-deserialization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

Skills/web/offensive-deserialization/SKILL.md · 601 lines

How it starts

The opening of the file, as written. The whole thing — 601 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Offensive Deserialization

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.

Quick Workflow

  1. Enumerate every entry point accepting opaque binary or encoded data -- cookies, HTTP bodies, headers, message queue messages, file uploads, GraphQL custom scalars, gRPC fields, JMX/RMI endpoints.
  2. Fingerprint the serialization format via magic bytes, content-type headers, and error behavior (see Recognition Signatures).
  3. Determine the server-side language and framework version from error pages, HTTP headers, or source code.
  4. Select candidate gadget chains matching the target classpath or installed packages. Generate payloads with ysoserial, phpggc, ysoserial.net, or manual construction.
  5. Deliver through the identified entry point. Start with DNS-only or sleep-based proof to confirm execution without destructive side effects.
  6. Escalate from proof-of-concept to the engagement objective with authorization.
  7. Document the full chain: entry point, format, gadget chain, library versions, proof.

Recognition Signatures

Format Signature Notes
Java ObjectInputStream Hex ac ed 00 05, Base64 rO0AB Cookies, POST bodies, JMX/RMI streams
PHP serialize O:<len>:"ClassName": or a:<count>:{ Frequently Base64-wrapped in cookies
.NET BinaryFormatter Base64 AAEAAAD///// ViewState, remoting, session state
Python pickle Opcodes \x80\x04\x95 (v4+), older (dp0 text Redis caches, Celery tasks, ML pipelines
Ruby Marshal \x04\x08 leading bytes Session cookies in older Rails apps
YAML (any lang) --- !ruby/object: or !!python/object/apply: Tag-based instantiation
Java XMLDecoder <?xml with <java> or <object class= Legacy Java admin panels
.NET Json.NET "$type": key in JSON TypeNameHandling != None
Java Jackson ["class.name", { JSON array wrapper enableDefaultTyping / polymorphic handling

Read the full file on GitHub · 601 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 601 lines · 189 tokens per session scan E 2dfb6f4dfa3b

Subscribe to this mod's changes

offensive-deserialization is a skill published in the GitHub repository SnailSploit/Claude-Red (7,620 stars, last pushed 8d ago), licensed MIT. It adds 189 tokens to every session and 5,748 once invoked, about $0.0008 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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