Trail of Bits

Fp Check — Security skill for Claude Code

Security community Advanced

Trail of Bits security skill for fp check.

How to install Fp Check

Installs to ~/.claude/skills/fp-check/

Terminal

git clone --depth 1 https://github.com/trailofbits/skills /tmp/skills \
  && mkdir -p ~/.claude/skills \
  && cp -r /tmp/skills/plugins/fp-check ~/.claude/skills/fp-check

Clones the whole repository, because a skill folder can carry scripts and resources beside its SKILL.md.

What Fp Check does

A Claude Code plugin that enforces systematic false positive verification when verifying suspected security bugs.

Alternatives in Security

Portaljs Check Data Quality — Audit a local or remote tabular file (CSV/TSV) for common data quality issues 2.3k ★
Trail Of Bits Claude-code-config — Opinionated production defaults from a top security firm: sandboxing, permissions, hooks, skills, MCP server c 1.6k ★
Convex Security Check 354 ★

Repository README

This is the README for trailofbits/skills, shared by 13 entries in this directory. It describes the repository, not this entry specifically.

fp-check

A Claude Code plugin that enforces systematic false positive verification when verifying suspected security bugs.

Overview

When Claude is asked to verify suspected security bugs, this plugin activates a rigorous per-bug verification process. Bugs are routed through one of two paths:

Standard verification — a linear single-pass checklist for straightforward bugs (clear claim, single component, well-understood bug class). No task creation overhead.
Deep verification — full task-based orchestration with parallel sub-phases for complex bugs (cross-component, race conditions, ambiguous claims, logic bugs without spec).

Both paths end with six mandatory gate reviews. Each bug receives a **TRUE POSITIVE** or **FALSE POSITIVE** verdict with documented evidence.

Installation

/plugin install fp-check

Components

Skills

Skill	Description
fp-check	Systematic false positive verification for security bug analysis

Agents

Agent	Phases	Description
data-flow-analyzer	1.1–1.4	Traces data flow from source to sink, maps trust boundaries, checks API contracts and environment protections
exploitability-verifier	2.1–2.4	Proves attacker control, creates mathematical bounds proofs, assesses race condition feasibility
poc-builder	4.1–4.5	Creates pseudocode, executable, unit test, and negative PoCs

Hooks

Hook	Event	Purpose
Verification completeness	Stop	Blocks the agent from stopping until all bugs have completed all 5 phases, gate reviews, and verdicts
Agent output completeness	SubagentStop	Blocks agents from stopping until they produce complete structured output for their assigned phases