hunting-os-command-injection SKILL.md skillA
hunting-os-command-injection from unboundcompute/security-agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add unboundcompute/security-agent-skills/hunting-os-command-injection@git:20260903.6dac719Pins git:20260903.6dac719 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- unboundcompute/security-agent-skills
- Path
skills/hunting-os-command-injection/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260903.6dac719, committed Sep 3, 2026
- Size
- 9,217 bytes
- Repository stars
- 26
- License
- MIT
Hunt OS command injection where untrusted input reaches a process-spawning API through a shell that interprets metacharacters. Covers a command string passed to a system or shell-exec call, a spawn that requests a shell, and indirect shells reached through wildcards, subshells, environment values, or an attacker-influenced PATH or IFS. The distinguishing fact is the shell: a direct exec with a fixed program and an argument vector does not interpret metacharacters and is not this bug, while any…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Hunting OS command injection: when input crosses into a shell Command injection happens when untrusted input reaches a process-spawning API in a way that lets a shell interpret it. A shell treats characters like the semicolon, the pipe, the ampersand, backticks, and dollar parentheses as syntax, so an input that carries them can chain, substitute, or replace the intended command. The single fact that decides whether the class exists is whether a shell is in the loop: a call that composes a string and hands it to a system shell is injectable, while a direct exec that passes a fixed program and a separate argument vector, with no shell, is not, because the arguments are delivered as data. You find command injection by locating every spawn, deciding whether it goes through a shell, and tracing whether untrusted input reaches the command portion of a shell-interpreted call. ## When to use - Code runs an external command built from, or including, request or stored input. - A spawn API is called in shell mode, or with a single composed string rather than an argument vector. - Input influences the environment, the working directory, or the PATH of a spawned process. ## Scope check …
Read the whole file at its exact version.
How to install
mdr add unboundcompute/security-agent-skills/hunting-os-command-injection@sha256:d783fe805f0181b8The line at the top of this page pins the label git:20260903.6dac719, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_ivggi2j4xle3hw5k)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Sep 3, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (9217 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
unboundcompute/security-agent-skills · 26 stars · license MIT · pushed 2026-09-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ivggi2j4xle3hw5k GET https://markdownregistry.com/api/v1/resolve?ref=unboundcompute/security-agent-skills/hunting-os-command-injection GET https://markdownregistry.com/api/v1/blob/d783fe805f0181b8e601734c05c73fdfb299945152824ce3e65b50f91aede59f
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.