agentleFS
mn-youssefmn-youssef/security-skills/skills/security-code-audit/SKILL.md

security-code-audit

Skill47 starsChanged 5 months agoMITView on GitHub

Use when you have application source code and want to find security vulnerabilities by reading it — covers OWASP Top 10 across frontend, backend API, and database. Produces a findings register with severity, file:line, and exploitability.

1 other project uses a version of this.

Adopted by

Most recently taken up by

The file

We split this skill into the rules it gives an agent

4 rules. About 0 are common, 3 are distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈3

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Read source code and find vulnerabilities by pattern.

    line 9
  2. Distinctive:

    Follow the data through the code to where it's used (the sink).

    line 18
  3. Distinctive:

    Ask: is it validated, sanitized, parameterized, or encoded *for that sink*?

    line 19
  4. Very specific:

    All findings → security-hardening to fix.

    line 50

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Security Code Audit (FIND phase)

Overview

Read source code and find vulnerabilities by pattern. No running app required — works in any AI coding tool. Trace untrusted input from its source (where it enters) to its sink (where it's used dangerously).

Core principle: A vulnerability is untrusted data reaching a dangerous sink without adequate validation/encoding in between. Find the source→sink paths.

Method: source → sink tracing

  1. From the threat model (or by scanning entry points), pick a source of untrusted input.
  2. Follow the data through the code to where it's used (the sink).
  3. Ask: is it validated, sanitized, parameterized, or encoded for that sink? If not → finding.
  4. Record severity, file:line, the exact data path, and how to exploit it.

OWASP Top 10 — what to grep for

RiskSmell / sink to search
Injection (SQL/NoSQL/cmd)string-built queries, exec, eval, system, template interpolation in queries
Broken access control (IDOR)object lookups by user-supplied id with no ownership check
Broken authcustom crypto, weak session handling, missing MFA, token in URL
Cryptographic failuresmd5/sha1 for passwords, hardcoded keys, Math.random for tokens, no TLS
SSRFserver fetches a user-supplied URL (requests.get(input), fetch(input))
Security misconfigdebug=true, default creds, permissive CORS *, verbose errors
XSSinnerHTML, dangerouslySetInnerHTML, v-html, unescaped template output
Insecure deserializationpickle.loads, yaml.load, native deserialize on input
Vulnerable dependenciescheck lockfiles vs advisories (npm audit, pip-audit, osv)
SSTI / path traversaltemplate render of input, ../ in file paths from input

Domain references (load the ones that match your stack)

  • references/web-frontend.md — XSS, CSRF, CSP, client-side secrets, clickjacking
  • references/api-backend.md — authz/IDOR, injection, SSRF, JWT, rate limiting, mass assignment
  • references/database.md — SQLi/NoSQLi, access control, data exposure, ORM pitfalls

Output: findings register

IDSeverityTitleLocationSource→sinkExploitabilityFix pointer
F1HighSQLi in user searchapi/users.py:42?q= → raw SQLUnauth, dumps DBparameterize → security-hardening

Severity = the threat-model risk score, adjusted for how exploitable the code actually is.

Hand-off

High-severity findings on a running app → active-pentest to validate. All findings → security-hardening to fix.

Common mistakes

  • Pattern-matching sinks without confirming input is actually attacker-controlled (false positive).
  • Stopping at the first sink — one source often reaches several.
  • Trusting client-side validation — it's bypassable; the server must validate.
  • Ignoring authorization: most real-world breaches are access control, not exotic injection.

Download now (ZIP)

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

No reviews yet

People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

  • It worked
  • Partly
  • It didn't
What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.