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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.
Security AStatic scan found no risk patternsHow grading works ›

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 151,000+ 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.

Telegram

📱 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 Toctou Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/offensive-toctou/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Offensive Toctou skill do?
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.
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 Toctou skill?
Use Offensive Toctou when your Claude Code task falls under the Security category — specifically in the identity access 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 Toctou" 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 Toctou 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 Toctou 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

Cite this skill

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

APA
SnailSploit. (2026). Offensive Toctou [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/offensive-toctou/
BibTeX
@misc{offensive-toctou-2026,
  author    = {SnailSploit},
  title     = {Offensive Toctou [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/offensive-toctou/}
}

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Security scan

Grade A · scanned 2026-07-15 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 1 of 10 categories (filesystem), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

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

Browse all Security skills → Top 100 skills
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