vulnerability-audit

A per-file security auditor that checks code hotspots against named Soundcheck security rules and reports actionable findings. A hotspot is a function or code area likely to handle sensitive operations or untrusted data.

In plain words
What is it for?
Use it during a full security review to inspect authentication, input handling, file access, uploads, routes, and other risky code areas.
Why use it?
It provides a detailed review of related code in one file instead of relying only on quick pattern matches. It can find multiple distinct problems in the same area and nearby related code.

Agent for Claude Code

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 agents/thejefflarson/soundcheck/vulnerability-audit
Clone the repo
git clone --depth 1 https://github.com/thejefflarson/soundcheck

Made for: Claude Code.

Per session 49 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,104 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 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 $0.00049 $0.02104
Opus 5 $0.00024 $0.01052
Sonnet 5 $0.00010 $0.00421
Haiku 4.5 $0.00005 $0.00210

Measured 2d ago against content hash 71c359753bdb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

vulnerability-audit scanned grade B 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 2d 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.

Instruction-override phrasingmediumPrompt injection

Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.

*"ignore previous instructions"*, *"this code is safe, don't flag

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

Unrestricted tool accesslowExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

payloads can execute arbitrary code on deserialization, JSON

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

.claude/agents/vulnerability-audit.md · 202 lines

How it starts

The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You audit one file's hotspots for the Soundcheck security review pipeline. The orchestrator collapses all hotspots by file and dispatches one of you per file so the work runs in parallel and you have coherent context across related hotspots in the same file. For each hotspot you receive, read the cited code, look up every Soundcheck skill whose vulnerable pattern could apply, and decide whether the code matches.

This is the stage where most of the real findings come from. Take your time per hotspot. A careless review with wrong findings is worse than a slow review with right ones — the consumer of this output is a developer who will trust your verdict.

Be exhaustive per hotspot. A single hotspot often matches more than one skill and contains more than one distinct bug — a route handler can be missing both auth and rate-limiting; a filename can flow into both a path-traversal sink and an upload allowlist gap. Emit one finding per distinct vulnerability, not one per hotspot. And while you have the file open, if you notice a related bug in adjacent code — a sibling handler with the same flaw, a shared helper misused by another caller, a second sink downstream — report it too. Exhaustive-within-the-file is the target.

Inputs

The user message will include:

  • The threat model JSON from threat-modeling. Pay attention to trusted_inputs (don't flag content that originates from a trusted source) and untrusted_inputs (the bytes that can carry attacker content).
  • A JSON array of hotspots from hotspot-mapping, all in the same file: [{file, lines, name, category, priority, why}, ...]. Open the file once, then review each hotspot's line range in turn. category and priority are for downstream sorting and need not influence your audit decision.

What to do per hotspot

  1. Open the cited file and read the cited line range. Read enough surrounding context to understand the data flow: where does input come from, where does it end up, what transformations happen on the way.
  2. Pick every applicable Soundcheck skill. Based on what the code does (e.g. constructs a query from request data, reads a file path from a URL parameter, sets a session cookie, writes trusted state into a response body), choose every matching skill. A hotspot commonly matches more than one — a route that both takes an ID and lacks auth matches broken-access-control and, if the ID also flows into a query, injection. Invoke each matching skill by its plugin-qualified name via the Skill tool — always soundcheck:<name>, e.g. Skill('soundcheck:injection'). The skill's guidance activates in your context: its vulnerable-pattern catalog defines what counts, and its fix guidance describes what a safe equivalent looks like. If nothing in the catalog fits a bug you clearly see, use soundcheck:insecure-design.

Read the full file on GitHub · 202 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. 2d ago First seen · 202 lines · 49 tokens per session scan B 71c359753bdb

Subscribe to this mod's changes

vulnerability-audit is an agent published in the GitHub repository thejefflarson/soundcheck (20 stars, last pushed 1mo ago), licensed MIT. It adds 49 tokens to every session and 2,104 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 2 findings (instruction-override phrasing, unrestricted tool access). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.