What is cmd-injection?

A security-testing guide for operating-system command injection, where user input is passed unsafely to a system shell. A shell is the program that runs operating-system commands.

It is for checking code that sends input to shell or command-execution functions, using separators, command substitutions, and time-delay tests.

It helps find inputs that let attackers add commands to an operation intended to run only a fixed command.

cmd-injection — Skill for Claude Code by securityfortech

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.

Any agent

npx skills add securityfortech/hacking-skills --skill cmd-injection

Clone the repo

git clone --depth 1 https://github.com/securityfortech/hacking-skills

Made for: Claude Code.

Or install web, the plugin that ships this one along with the rest of its 28 skills.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/securityfortech/hacking-skills/cmd-injection/github.svg)](https://agentmods.dev/skills/securityfortech/hacking-skills/cmd-injection)

Your own site

<a href="https://agentmods.dev/skills/securityfortech/hacking-skills/cmd-injection"><img src="https://agentmods.dev/badge/skills/securityfortech/hacking-skills/cmd-injection/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/securityfortech/hacking-skills/cmd-injection"><img src="https://agentmods.dev/badge/skills/securityfortech/hacking-skills/cmd-injection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,742 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 2 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown 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.

Model	Per session	Once invoked
Fable 5.1	$0.00104	$0.01742
Opus 5.5	$0.00042	$0.00697
Sonnet 5.5	$0.00021	$0.00348
Haiku 4.5	$0.00010	$0.00174

Measured 2mo ago against content hash f1d431eedecb, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cmd-injection scanned grade A with 2 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 2mo 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.

Makes network callslowCapability

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

compatibility: Designed for Claude Code. Requires curl, Burp Suite or OWASP ZAP, Commix (optional).

Runs shell commandslowCapability

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

OS command injection occurs when user input is passed unsanitized to a system shell via dangerous APIs: Java `Runtime.exec()`, Python `os.system/subprocess`, PHP `system/shell_exec/exec/proc_open`, C `system/exec`. Detec

skills/web/injection/cmd-injection/SKILL.md · 119 lines

The source is not reproduced here

No licence file

Read it on GitHub

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.

2mo ago First seen · 119 lines · 104 tokens per session scan A f1d431eedecb

Subscribe to this mod's changes

cmd-injection is a skill published in the GitHub repository securityfortech/hacking-skills (21 stars, last pushed 7mo ago), with no licence file. It adds 104 tokens to every session and 1,742 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 2 findings (makes network calls, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Security

cmd-injection next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
cmd-injectionsecurityfortech/hacking-skills	Skill	21	7mo ago	none	A	104	Claude Code
imagegenopenai/codex	Skill	133k	yesterday	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	yesterday	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	4d ago	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	313k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	103	Claude Code

cmd-injection

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Makes network callslowCapability

Runs shell commandslowCapability

The source is not reproduced here

No licence file

What this file has done since we first saw it

cmd-injection compared with skills from other repositories