competition-kernel-container-escape

A specialized CTF workflow for investigating whether a process inside a container can cross into the host through the Linux kernel or container boundary.

In plain words
What is it for?
It is for examining namespaces, cgroups, capabilities, system-call restrictions, security controls, mounts, runtime sockets, kernel details, and a minimal container-to-host escape path.
Why use it?
It helps distinguish an exploit prerequisite from a working escape and records the evidence needed to show that the boundary was actually crossed.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/zhaoxuya520/reverse-skill/competition-kernel-container-escape
Any agent
npx skills add zhaoxuya520/reverse-skill --skill competition-kernel-container-escape
Clone the repo
git clone --depth 1 https://github.com/zhaoxuya520/reverse-skill

Made for: Claude Code, Codex.

Per session 102 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 580 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00102 $0.00580
Opus 5 $0.00051 $0.00290
Sonnet 5 $0.00020 $0.00116
Haiku 4.5 $0.00010 $0.00058

Measured yesterday against content hash c6e840b0365e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

competition-kernel-container-escape 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 yesterday.

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

4 near-identical copies found in the catalogue:

CTF-Sandbox-Orchestrator/competition-kernel-container-escape/SKILL.md · 51 lines

How it starts

The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Competition Kernel Container Escape

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the decisive step is proving a boundary crossing between containerized context and host or higher-privilege kernel context.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Map runtime isolation first: namespaces, cgroups, seccomp, capabilities, LSM, and mount boundaries.
  2. Separate exploit prerequisite, primitive, and boundary-crossing proof.
  3. Record kernel version, config hints, runtime options, and reachable syscall surface.
  4. Keep instrumented observations separate from pristine challenge path.
  5. Reproduce one minimal primitive-to-boundary-crossing chain.

Workflow

1. Map Isolation And Kernel Surface

  • Record namespace map, cgroup mode, capabilities, seccomp profile, AppArmor or SELinux state, mounted filesystems, and runtime sockets.
  • Note kernel version, distro build hints, module exposure, and container runtime behavior.
  • Keep host and container observations linked to exact node and context.

2. Prove Exploit Primitive And Crossover

  • Show controllable input, trigger condition, affected object, and observable kernel or runtime state change.
  • Capture before and after identity, namespace, mount, or process visibility to prove boundary crossing.
  • Distinguish crash-only behavior from stable capability gain.

3. Reduce To Decisive Escape Chain

  • Compress to: prerequisite state -> primitive trigger -> boundary crossing evidence -> resulting host-level capability.
  • State whether root cause is kernel vulnerability, runtime misconfiguration, capability overgrant, or namespace leak.
  • If path relies mostly on credential replay after initial foothold, hand off to Linux credential pivot skill.

Read the full file on GitHub · 51 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. yesterday First seen · 51 lines · 102 tokens per session scan A c6e840b0365e

Subscribe to this mod's changes

competition-kernel-container-escape is a skill published in the GitHub repository zhaoxuya520/reverse-skill (31,677 stars, last pushed 5d ago), licensed MIT. It adds 102 tokens to every session and 580 once invoked, about $0.0005 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 2026-08-30.

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