Detecting Insecure Deserialization

What it does

When your agent uses it

• : pre-commit gate on services that accept binary blobs
• Audit of legacy job-queue code (workers deserializing tasks)
• Untrusted storage
• With: scan deserialization

Example prompts

• “we accept user-uploaded archives.”
• “scan deserialization”
• “pickle audit”
• “/detecting-insecure-deserialization”

Requirements

• Python 3
• Node.js
• Compatibility (from SKILL.md): Designed for Claude Code
• Pre-approved tools (allowed-tools): Read, Bash(python3:*), Glob, Grep

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Bash(python3:*)
  • Glob
  • Grep

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 1 file in scripts/ (Python), which the agent can run.

  Shell commands in SKILL.md call:

  • python3

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Designed for Claude Code

  From compatibility in the SKILL.md frontmatter.

Context cost

Detecting Insecure Deserialization loads about 1.4k tokens when it runs, and up to ~5.2k if it reads all its reference files. Until then it costs about 199 tokens; SKILL.md has 404 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~199

When it runs · the whole SKILL.md, loaded when a task matches

~1.4k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~5.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 404 words, ~1,360 tokens.

name

detecting-insecure-deserialization

description

Scan a source tree for unsafe-by-default deserialization APIs: Python pickle.loads / cPickle / shelve / dill, Ruby Marshal.load / YAML.load (pre-3.1 default), Java ObjectInputStream.readObject, PHP unserialize, .NET BinaryFormatter / NetDataContractSerializer, Node.js node-serialize, JavaScript JSON.parse with reviver containing eval. Use when: pre-commit gate on services that accept binary blobs, audit of legacy job-queue code (workers deserializing tasks), post-bug-report when "we accept user-uploaded archives." Threshold: any call to a known-unsafe deserialization API on data that originates from user input, network, file upload, or untrusted storage. Trigger with: "scan deserialization", "pickle audit", "java readObject scan", "yaml.load check".

allowed-tools

Read, Bash(python3:*), Glob, Grep

compatibility

Designed for Claude Code

disallowed-tools

Bash(rm:*), Bash(curl:*)

version

3.30.0

author

Jeremy Longshore <jeremy@intentsolutions.io>

license

MIT

tags

security, static-analysis, deserialization, pentest

python3 ${CLAUDE_PLUGIN_ROOT}/skills/detecting-insecure-deserialization/scripts/scan_deserialization.py /path/to/repo

python3 ${CLAUDE_PLUGIN_ROOT}/skills/detecting-insecure-deserialization/scripts/scan_deserialization.py \
    /path/to/celery-workers --min-severity high

- name: Deserialization scan
  run: |
    python3 plugins/security/penetration-tester/skills/detecting-insecure-deserialization/scripts/scan_deserialization.py \
        . --min-severity high

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (scripts, references) in skills/.curated/detecting-insecure-deserialization of jeremylongshore/tons-of-skills-marketplace.

• SKILL.md
• references/PLAYBOOK.md
• references/THEORY.md
• scripts/scan_deserialization.py

Open the folder on GitHubat commit cfae287