sandbox-escape-techniques

sandbox-escape-techniques is a skill for Claude Code, Codex from yaklang/hack-skills. It costs 49 tokens per session (2,442 once invoked), scanned A, original, MIT.

A security testing guide for escaping restricted environments such as Python sandboxes, containers, browser sandboxes, or Linux isolation features. A sandbox is a controlled space intended to limit code and file access.

In plain words
What is it for?
Use it to examine Python and Lua jails, seccomp filters, chroot environments, Docker and namespace isolation, and browser sandbox escapes.
Why use it?
It helps assess whether isolation boundaries can be bypassed to gain broader execution or access.

Skill for Claude CodeCodex

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is │ ├── See ../container-escape-techniques/SKILL.md.

Good fit Use it to examine Python and Lua jails, seccomp filters, chroot environments, Docker and namespace isolation, and browser sandbox escapes.

Compare 6 skills from other repositories ↓
About the project

HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.

yaklang/hack-skills · 2,143 stars · on GitHub

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/yaklang/hack-skills
agentmods
npx agentmods add skills/yaklang/hack-skills/sandbox-escape-techniques

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 sandbox-escape-techniques

README.md
[![agentmods](https://agentmods.dev/badge/skills/yaklang/hack-skills/sandbox-escape-techniques/github.svg)](https://agentmods.dev/skills/yaklang/hack-skills/sandbox-escape-techniques)
Your own site
<a href="https://agentmods.dev/skills/yaklang/hack-skills/sandbox-escape-techniques"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/sandbox-escape-techniques/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 sandbox-escape-techniques

Your own site · 80×15
<a href="https://agentmods.dev/skills/yaklang/hack-skills/sandbox-escape-techniques"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/sandbox-escape-techniques.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,442 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
  • Socket fail 9 Apr 2026
  • Snyk fail 9 Apr 2026
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 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 Privilege Escalation · line 172
    Potential security issue detected. Manual review is recommended.
    Fix: Review the flagged content for security risks. Ensure no credentials, secrets, or sensitive data are exposed.
  • high Privilege Escalation · line 181
    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.
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 $0.00049 $0.02442
Opus 5 $0.00024 $0.01221
Sonnet 5 $0.00010 $0.00488
Haiku 4.5 $0.00005 $0.00244

Measured 6d ago against content hash ea0ddc8359cf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

sandbox-escape-techniques 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 6d 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

3 near-identical copies found in the catalogue:

skills/sandbox-escape-techniques/SKILL.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Sandbox Escape — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert sandbox escape techniques across Python, Lua, seccomp, chroot, Docker/container, and browser sandbox contexts. Covers CTF pyjail patterns, seccomp architecture confusion, chroot fd leaks, namespace escape, and Mojo IPC abuse. Distilled from ctf-wiki sandbox sections and real-world container escapes. Base models often miss the distinction between sandbox types and apply wrong escape techniques.

Advanced References

  • PYTHON_SANDBOX_ESCAPE.md — Full pyjail methodology: __builtins__ recovery, keyword bypass, AST bypass, pickle escape
  • SECCOMP_BYPASS.md — Architecture confusion, io_uring bypass, ptrace bypass, allowed syscall chaining

1. SANDBOX TYPE IDENTIFICATION

Sandbox Type Indicators Typical Context
Python sandbox (pyjail) Limited builtins, filtered keywords, exec/eval available CTF, online judges, Jupyter
Lua sandbox No os, io modules; restricted metatables Game scripting, config
seccomp syscall filtering, prctl(PR_SET_SECCOMP) CTF pwn, container hardening
chroot Changed root filesystem, limited /proc access Legacy isolation
Docker/container Namespaces, cgroups, reduced capabilities Cloud, microservices
Browser (renderer) OS-level sandbox (seccomp-bpf + namespaces on Linux) Chrome, Firefox
Namespace isolation PID/mount/network/user namespace Container runtimes

Read the full file on GitHub · 251 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago First seen · 251 lines · 49 tokens per session scan E ea0ddc8359cf

Subscribe to this mod's changes

sandbox-escape-techniques is a skill published in the GitHub repository yaklang/hack-skills (2,143 stars, last pushed 2mo ago), licensed MIT. It adds 49 tokens to every session and 2,442 once invoked, about $0.0002 per session on Opus 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 2026-09-03.

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