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Offensive Toctou

Category: Security  ·  Sub-category: identity-access  ·  Last updated:
tool:k8s
Time-of-Check / Time-of-Use (TOCTOU) race condition exploitation methodology across binary, kernel, filesystem, web, and container layers. Covers symbolic-link races (open/access/stat split), file-descriptor races, fopen/realpath traversal races, /proc and procfs races, FUSE-backed slow-fs races to widen the window, ptrace and signal races, kernel double-fetch / userspace pointer races, container/runc/symlink escape primitives, kubernetes admission/authz TOCTOU, web auth-vs-authz TOCTOU, JWT-claim TOCTOU at gateway vs service, payment/idempotency races, and modern race-amplification techniques (single-packet attack, slow loris, FUSE pause, cgroup freeze, scheduler shaping). Use when you've identified a 'check then act' pattern in code, when fuzzing for race conditions, or when exploiting concurrency bugs in privileged binaries / kernel / orchestrators.

From the source SKILL.md

A TOCTOU bug exists wherever code checks a property (file owner, path target, token validity, balance) and then acts on it as if the property still holds. Between check and use is a window — your job is to widen it and swap the underlying object.

What this skill does

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

When to invoke it: Use when you've identified a 'check then act' pattern in code, when fuzzing for race conditions, or when exploiting concurrency bugs in privileged binaries / kernel / orchestrators.

Who uses this skill

The Offensive Toctou 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 69,000+ 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-toctou
curl -L https://claudskills.com/skills/offensive-toctou/SKILL.md \
  -o ~/.claude/skills/offensive-toctou/SKILL.md

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

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

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

Attribution & license

More Security skills

Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills
Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills.  ·  What's New  ·  Install guide  ·  About  ·  llms.txt

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