Kevin Veen-BirkenbachandClaude Opus 5.5
6540e4e4f1
security.py caches findings for 24 h, keyed by content, mode, the medusa binary, PATH and MEDUSA_ variables, in an owner-only directory, and runs medusa with min(files, 4) workers. Committed below the bar on the operator's word 2026-11-12 (one gate after the merge): test_security 14 green, the before-and-after measurement never ran; the GOMAXPROCS cap stays unstaged. 🎯 Fix: 70 % 💥 Break: 10 % 💸 Cost: 100 % ⏱️ Time: 100 % 🛡️ Security: 95 % 🏆 Score: 60 🚦 Gate: ⛔ fix 70 % < 90, break 10 % > 5; security 95 % < 100: ask the operator before the commit Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
3.4 KiB
name, description
| name | description |
|---|---|
| kvb-check-security | MEDUSA security scan of a repository, working tree or secret stores: vetting a repo, leaked secrets in chat or shell history. Defensive only. |
MEDUSA is a defensive AI-first security scanner (40,000+ patterns: CVEs, prompt injection, MCP tool poisoning, leaked secrets).
Setup
Check availability with medusa --version.
The skills repository's make install installs it with pipx; if it is still missing, pipx install medusa-security (fallback: pip install --user medusa-security) is the operator's step.
Commands
| Task | Command |
|---|---|
| Scan the current project | medusa scan . |
Vet a remote repo BEFORE cloning (supply chain, poisoned .claude/ hooks, permissions, skills) |
medusa scan --git <url-or-org/repo> |
| Find leaked API keys in AI chat + shell history | medusa secrets scan |
| Scan one exported file | medusa secrets scan --path <file> |
Security value of a change
The 🛡️ value of the kvb-check-score block, 100 % meaning safe:
python3 ${CLAUDE_SKILL_DIR}/scripts/security.py --repo <root> --base <ref>
It copies the files changed since <ref>, untracked ones included and
symlinks left out, to a temporary tree, scans it once with
medusa scan <tree> --format json -o <dir> --no-cache --workers <w> (w at
most WORKERS of the script) and prints one line:
🛡️ security <n> % (medusa: <k> findings in <m> files: <severity> <path>:<line>, ...).
<n> is 100 minus 50 per critical, 25 per high, 10 per medium and 2 per low
finding, at least 0. It shows locations and counts only, never a matched
value. Pass <n> as --security and the critical count as --critical
(--json holds it) to score.py. A rescan of byte-identical files with the
same medusa reuses the findings in <council root>/security-cache/ for
CACHE_SECONDS instead of running medusa again.
- Exit 0: 100 %. Exit 3: below 100 without a critical finding; the score gate asks the operator. Exit 1: a critical finding; the score gate forbids the commit.
- Exit 4: medusa is missing or its report unreadable. Review trust
boundaries, secrets and injection in the diff by hand, then pass
--security '~<n>'(quoted: zsh expands a bare~100as a user's home) and the critical findings you found as--critical. - Exit 2: usage error.
- Accepted false positives:
security.py accept --repo <root> --rule <id> [--rule <id> ...] --path <path> --sha1 <sha1> --line <n> --reason "<one line>"(from--json) appends a row per rule to the council root, which thekvb-org-organizewatch hook mirrors to~/.local/state/agents-council/. A match leaves the score as<a> accepteduntil the line or its neighbourhood changes;--lineis required when the same text occurs on several lines, so one acceptance never hides an identical line. Accept only afterkvb-think-criticizejudged it a false positive or by design; name each acceptance in the commit message.
Rules
- Run scans read-only; never pass
--revealand never runmedusa secrets purgeunless the user explicitly asks for it. - Summarize findings by severity with file/line references; do not paste secret values into the conversation, even redacted ones.
- Treat findings as signals for review, not verdicts; confirm true positives in the code before proposing fixes.
- Vet third-party agent repos (
medusa scan --git) before recommending the user clone or install them.