zeroize-audit — Claude Skill

When to Use

• Auditing cryptographic implementations (keys, seeds, nonces, secrets)
• Reviewing authentication systems (passwords, tokens, session data)
• Analyzing code that handles PII or sensitive credentials
• Verifying secure cleanup in security-critical codebases
• Investigating memory safety of sensitive data handling

When NOT to Use

• General code review without security focus
• Performance optimization (unless related to secure wiping)
• Refactoring tasks not related to sensitive data
• Code without identifiable secrets or sensitive values

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How to Run

On a request like "audit this crate for secrets left in memory" or "check that this C library actually wipes its keys":

1. Collect inputs. Map the request onto the Inputs table below (full schema: {baseDir}/schemas/input.json). path is required, plus at least one of compile_db (C/C++) or cargo_manifest (Rust); if neither is given or derivable from the repo, ask the user, because preflight stops the run without one. Leave all other fields at their defaults unless the user says otherwise.
2. Read the orchestrator prompt, {baseDir}/prompts/task.md, substituting the collected inputs for its {{placeholder}} values. You act as the orchestrator it describes: it defines state recovery, the phase loop, early termination, and error handling. Read {baseDir}/prompts/system.md alongside it for the shared working-directory layout and the agent error protocol every phase depends on.
3. Execute its phase loop. Run Phases 0-7 sequentially. Before each phase, read that phase's workflow file from {baseDir}/workflows/phase-{N}-{name}.md and follow its Preconditions, Instructions, State Update, and Error Handling sections. Each workflow specifies which agent to spawn via Task and with what parameters. Honor the per-phase skip conditions and the early-termination rules in task.md.
4. Return the report (Phase 8, inline): read {workdir}/report/final-report.md and return its contents as the skill output.

To resume an interrupted run: if a workdir is known from prior context, read {workdir}/orchestrator-state.json and continue from its current_phase instead of starting at Phase 0 (see the Recovery section of task.md).

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Purpose

Detect missing zeroization of sensitive data in source code and identify zeroization that is removed or weakened by compiler optimizations (e.g., dead-store elimination), with mandatory LLVM IR/asm evidence. Capabilities include:

• Assembly-level analysis for register spills and stack retention
• Data-flow tracking for secret copies
• Heap allocator security warnings
• Semantic IR analysis for loop unrolling and SSA form
• Control-flow graph analysis for path coverage verification
• Runtime validation test generation

Scope

• Read-only against the target codebase (does not modify audited code; writes analysis artifacts to a temporary working directory).
• Produces a structured report (JSON).
• Requires valid build context (compile_commands.json) and compilable translation units.
• "Optimized away" findings only allowed with compiler evidence (IR/asm diff).

---

Inputs

See {baseDir}/schemas/input.json for the full schema. Key fields:

Field	Required	Default	Description
path	yes	—	Repo root
compile_db	no	null	Path to compile_commands.json for C/C++ analysis. Required if cargo_manifest is not set.
cargo_manifest	no	null	Path to Cargo.toml for Rust crate analysis. Required if compile_db is not set.
config	no	—	YAML defining heuristics and approved wipes
opt_levels	no	["O0","O1","O2"]	Optimization levels for IR comparison. O1 is the diagnostic level: if a wipe disappears at O1 it is simple DSE; O2 catches more aggressive eliminations.
languages	no	["c","cpp","rust"]	Languages to analyze
max_tus	no	50	Limit on translation units processed from compile DB
mcp_mode	no	prefer	off, prefer, or require — controls Serena MCP usage
mcp_required_for_advanced	no	true	Downgrade SECRET_COPY, MISSING_ON_ERROR_PATH, and NOT_DOMINATING_EXITS to needs_review when MCP is unavailable
mcp_timeout_ms	no	10000	Timeout budget for MCP semantic queries
poc_categories	no	all 11 exploitable	Finding categories for which to generate PoCs. C/C++ findings: all 11 categories supported. Rust findings: only MISSING_SOURCE_ZEROIZE, SECRET_COPY, and PARTIAL_WIPE are supported; other Rust categories are marked poc_supported=false.
poc_output_dir	no	generated_pocs/	Output directory for generated PoCs
enable_asm	no	true	Enable assembly emission and analysis (Step 8); produces STACK_RETENTION, REGISTER_SPILL. Auto-disabled if emit_asm.sh is missing.
enable_semantic_ir	no	false	Enable semantic LLVM IR analysis (Step 9); produces LOOP_UNROLLED_INCOMPLETE
enable_cfg	no	false	Enable control-flow graph analysis (Step 10); produces MISSING_ON_ERROR_PATH, NOT_DOMINATING_EXITS
enable_runtime_tests	no	false	Enable runtime test harness generation (Step 11)

---

Prerequisites

Before running, verify the following. Each has a defined failure mode.

C/C++ prerequisites:

Prerequisite	Failure mode if missing
compile_commands.json at compile_db path	Fail fast — do not proceed
clang on PATH	Fail fast — IR/ASM analysis impossible
uvx on PATH (for Serena)	If mcp_mode=require: fail. If mcp_mode=prefer: continue without MCP; downgrade affected findings per Confidence Gating rules.
{baseDir}/tools/extract_compile_flags.py	Fail fast — cannot extract per-TU flags
{baseDir}/tools/emit_ir.sh	Fail fast — IR analysis impossible
{baseDir}/tools/emit_asm.sh	Warn and skip assembly findings (STACK_RETENTION, REGISTER_SPILL)
{baseDir}/tools/mcp/check_mcp.sh	Warn and treat as MCP unavailable
{baseDir}/tools/mcp/normalize_mcp_evidence.py	Warn and use raw MCP output

Rust prerequisites:

Prerequisite	Failure mode if missing
Cargo.toml at cargo_manifest path	Fail fast — do not proceed
cargo check passes	Fail fast — crate must be buildable
cargo +nightly on PATH	Fail fast — nightly required for MIR and LLVM IR emission
uv on PATH	Fail fast — required to run Python analysis scripts
{baseDir}/tools/validate_rust_toolchain.sh	Warn — run preflight manually. Checks all tools, scripts, nightly, and optionally cargo check. Use --json for machine-readable output, --manifest to also validate the crate builds.
{baseDir}/tools/emit_rust_mir.sh	Fail fast — MIR analysis impossible (--opt, --crate, --bin/--lib supported; --out can be file or directory)
{baseDir}/tools/emit_rust_ir.sh	Fail fast — LLVM IR analysis impossible (--opt required; --crate, --bin/--lib supported; --out must be .ll)
{baseDir}/tools/emit_rust_asm.sh	Warn and skip assembly findings (STACK_RETENTION, REGISTER_SPILL). Supports --opt, --crate, --bin/--lib, --target, --intel-syntax; --out can be .s file or directory.
{baseDir}/tools/diff_rust_mir.sh	Warn and skip MIR-level optimization comparison. Accepts 2+ MIR files, normalizes, diffs pairwise, and reports first opt level where zeroize/drop-glue patterns disappear.
{baseDir}/tools/scripts/semantic_audit.py	Warn and skip semantic source analysis
{baseDir}/tools/scripts/find_dangerous_apis.py	Warn and skip dangerous API scan
{baseDir}/tools/scripts/check_mir_patterns.py	Warn and skip MIR analysis
{baseDir}/tools/scripts/check_llvm_patterns.py	Warn and skip LLVM IR analysis
{baseDir}/tools/scripts/check_rust_asm.py	Warn and skip Rust assembly analysis (STACK_RETENTION, REGISTER_SPILL, drop-glue checks). Dispatches to check_rust_asm_x86.py (production) or check_rust_asm_aarch64.py (EXPERIMENTAL — AArch64 findings require manual verification).
{baseDir}/tools/scripts/check_rust_asm_x86.py	Required by check_rust_asm.py for x86-64 analysis; warn and skip if missing
{baseDir}/tools/scripts/check_rust_asm_aarch64.py	Required by check_rust_asm.py for AArch64 analysis (EXPERIMENTAL); warn and skip if missing

Common prerequisite:

Prerequisite	Failure mode if missing
{baseDir}/tools/generate_poc.py	Fail fast — PoC generation is mandatory

---

Approved Wipe APIs

The following are recognized as valid zeroization. Configure additional entries in {baseDir}/configs/.

C/C++

• explicit_bzero
• memset_s
• SecureZeroMemory
• OPENSSL_cleanse
• sodium_memzero
• Volatile wipe loops (pattern-based; see volatile_wipe_patterns in {baseDir}/configs/default.yaml)
• In IR: llvm.memset with volatile flag, volatile stores, or non-elidable wipe call

Rust

• zeroize::Zeroize trait (zeroize() method)
• Zeroizing<T> wrapper (drop-based)
• ZeroizeOnDrop derive macro

---

Finding Capabilities

Findings are grouped by required evidence. Only attempt findings for which the required tooling is available.

Finding ID	Description	Requires	PoC Support
MISSING_SOURCE_ZEROIZE	No zeroization found in source	Source only	Yes (C/C++ + Rust)
PARTIAL_WIPE	Incorrect size or incomplete wipe	Source only	Yes (C/C++ + Rust)
NOT_ON_ALL_PATHS	Zeroization missing on some control-flow paths (heuristic)	Source only	Yes (C/C++ only)
SECRET_COPY	Sensitive data copied without zeroization tracking	Source + MCP preferred	Yes (C/C++ + Rust)
INSECURE_HEAP_ALLOC	Secret uses insecure allocator (malloc vs. secure_malloc)	Source only	Yes (C/C++ only)
OPTIMIZED_AWAY_ZEROIZE	Compiler removed zeroization	IR diff required (never source-only)	Yes
STACK_RETENTION	Stack frame may retain secrets after return	Assembly required (C/C++); LLVM IR alloca+lifetime.end evidence (Rust); assembly corroboration upgrades to confirmed	Yes (C/C++ only)
REGISTER_SPILL	Secrets spilled from registers to stack	Assembly required (C/C++); LLVM IR load+call-site evidence (Rust); assembly corroboration upgrades to confirmed	Yes (C/C++ only)
MISSING_ON_ERROR_PATH	Error-handling paths lack cleanup	CFG or MCP required	Yes
NOT_DOMINATING_EXITS	Wipe doesn't dominate all exits	CFG or MCP required	Yes
LOOP_UNROLLED_INCOMPLETE	Unrolled loop wipe is incomplete	Semantic IR required	Yes

---

Agent Architecture

The analysis pipeline uses 11 agents across 8 phases, invoked by the orchestrator ({baseDir}/prompts/task.md) via Task. Agents write persistent finding files to a shared working directory (/tmp/zeroize-audit-{run_id}/), enabling parallel execution and protecting against context pressure.

Agent	Phase	Purpose	Output Directory
0-preflight	Phase 0	Preflight checks (tools, toolchain, compile DB, crate build), config merge, workdir creation, TU enumeration	{workdir}/
1-mcp-resolver	Phase 1, Wave 1 (C/C++ only)	Resolve symbols, types, and cross-file references via Serena MCP	mcp-evidence/
2-source-analyzer	Phase 1, Wave 2a (C/C++ only)	Identify sensitive objects, detect wipes, validate correctness, data-flow/heap	source-analysis/
2b-rust-source-analyzer	Phase 1, Wave 2b (Rust only, parallel with 2a)	Rustdoc JSON trait-aware analysis + dangerous API grep	source-analysis/
3-tu-compiler-analyzer	Phase 2, Wave 3 (C/C++ only, N parallel)	Per-TU IR diff, assembly, semantic IR, CFG analysis	compiler-analysis/{tu_hash}/
3b-rust-compiler-analyzer	Phase 2, Wave 3R (Rust only, single agent)	Crate-level MIR, LLVM IR, and assembly analysis	rust-compiler-analysis/
4-report-assembler	Phase 3 (interim) + Phase 6 (final)	Collect findings from all agents, apply confidence gates; merge PoC results and produce final report	report/
5-poc-generator	Phase 4	Craft bespoke proof-of-concept programs (C/C++: all categories; Rust: MISSING_SOURCE_ZEROIZE, SECRET_COPY, PARTIAL_WIPE)	poc/
5b-poc-validator	Phase 5	Compile and run all PoCs	poc/
5c-poc-verifier	Phase 5	Verify each PoC proves its claimed finding	poc/
6-test-generator	Phase 7 (optional)	Generate runtime validation test harnesses	tests/

The orchestrator reads one per-phase workflow file from {baseDir}/workflows/ at a time, and maintains orchestrator-state.json for recovery after context compression. Agents receive configuration by file path (config_path), not by value.

Execution flow

Phase 0: 0-preflight agent — Preflight + config + create workdir + enumerate TUs
           → writes orchestrator-state.json, merged-config.yaml, preflight.json
Phase 1: Wave 1:  1-mcp-resolver              (skip if mcp_mode=off OR language_mode=rust)
         Wave 2a: 2-source-analyzer           (C/C++ only; skip if no compile_db)  ─┐ parallel
         Wave 2b: 2b-rust-source-analyzer     (Rust only; skip if no cargo_manifest) ─┘
Phase 2: Wave 3:  3-tu-compiler-analyzer x N  (C/C++ only; parallel per TU)
         Wave 3R: 3b-rust-compiler-analyzer   (Rust only; single crate-level agent)
Phase 3: Wave 4:  4-report-assembler          (mode=interim → findings.json; reads all agent outputs)
Phase 4: Wave 5:  5-poc-generator             (C/C++: all categories; Rust: MISSING_SOURCE_ZEROIZE, SECRET_COPY, PARTIAL_WIPE; other Rust findings: poc_supported=false)
Phase 5: PoC Validation & Verification
           Step 1: 5b-poc-validator agent      (compile and run all PoCs)
           Step 2: 5c-poc-verifier agent       (verify each PoC proves its claimed finding)
           Step 3: Orchestrator presents verification failures to user via AskUserQuestion
           Step 4: Orchestrator merges all results into poc_final_results.json
Phase 6: Wave 6: 4-report-assembler           (mode=final → merge PoC results, final-report.md)
Phase 7: Wave 7: 6-test-generator             (optional)
Phase 8: Orchestrator — Return final-report.md

Cross-Reference Convention

IDs are namespaced per agent to prevent collisions during parallel execution:

Entity	Pattern	Assigned By
Sensitive object (C/C++)	SO-0001–SO-4999	2-source-analyzer
Sensitive object (Rust)	SO-5000–SO-9999 (Rust namespace)	2b-rust-source-analyzer
Source finding (C/C++)	F-SRC-NNNN	2-source-analyzer
Source finding (Rust)	F-RUST-SRC-NNNN	2b-rust-source-analyzer
IR finding (C/C++)	F-IR-{tu_hash}-NNNN	3-tu-compiler-analyzer
ASM finding (C/C++)	F-ASM-{tu_hash}-NNNN	3-tu-compiler-analyzer
CFG finding	F-CFG-{tu_hash}-NNNN	3-tu-compiler-analyzer
Semantic IR finding	F-SIR-{tu_hash}-NNNN	3-tu-compiler-analyzer
Rust MIR finding	F-RUST-MIR-NNNN	3b-rust-compiler-analyzer
Rust LLVM IR finding	F-RUST-IR-NNNN	3b-rust-compiler-analyzer
Rust assembly finding	F-RUST-ASM-NNNN	3b-rust-compiler-analyzer
Translation unit	TU-{hash}	Orchestrator
Final finding	ZA-NNNN	4-report-assembler

Every finding JSON object includes related_objects, related_findings, and evidence_files fields for cross-referencing between agents.

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Detection Strategy

Analysis runs in two phases. For complete step-by-step guidance, see {baseDir}/references/detection-strategy.md.

Phase	Steps	Findings produced	Required tooling
Phase 1 (Source)	1–6	MISSING_SOURCE_ZEROIZE, PARTIAL_WIPE, NOT_ON_ALL_PATHS, SECRET_COPY, INSECURE_HEAP_ALLOC	Source + compile DB
Phase 2 (Compiler)	7–12	OPTIMIZED_AWAY_ZEROIZE, STACK_RETENTION, REGISTER_SPILL, LOOP_UNROLLED_INCOMPLETE†, MISSING_ON_ERROR_PATH‡, NOT_DOMINATING_EXITS‡	clang, IR/ASM tools

* requires enable_asm=true (default) † requires enable_semantic_ir=true ‡ requires enable_cfg=true

For Rust, {baseDir}/references/rust-zeroization-patterns.md catalogues 40 named anti-patterns, keyed to the script that detects each one: Section A for rustdoc-JSON semantics (semantic_audit.py), Section B for dangerous APIs (find_dangerous_apis.py), and Section C for MIR/LLVM IR/assembly (check_mir_patterns.py, check_llvm_patterns.py, check_rust_asm.py). Read the relevant section when triaging a Rust finding, writing its fix recommendation, or deciding whether a hand-spotted pattern is already covered.

Two limits on how far that reference goes. The 34 entries in Sections A-C are what the scripts detect today; Section D's six are known gaps no script covers, so treat those as unaudited rather than clean. Sections A and C are also partial — the scripts emit some classes with no entry — so a finding that matches no catalogued pattern is still a finding, carrying whatever evidence the script produced.

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Output Format

Each run produces two outputs:

1. final-report.md — Comprehensive markdown report (primary human-readable output)
2. findings.json — Structured JSON matching {baseDir}/schemas/output.json (for machine consumption and downstream tools)

Markdown Report Structure

The markdown report (final-report.md) contains these sections:

• Header: Run metadata (run_id, timestamp, repo, compile_db, config summary)
• Executive Summary: Finding counts by severity, confidence, and category
• Sensitive Objects Inventory: Table of all identified objects with IDs, types, locations
• Findings: Grouped by severity then confidence. Each finding includes location, object, all evidence (source/IR/ASM/CFG), compiler evidence details, and recommended fix
• Superseded Findings: Source findings replaced by CFG-backed findings
• Confidence Gate Summary: Downgrades applied and overrides rejected
• Analysis Coverage: TUs analyzed, agent success/failure, features enabled, and any Section D patterns the crate uses that no script audits
• Appendix: Evidence Files: Mapping of finding IDs to evidence file paths

Structured JSON

The findings.json file follows the schema in {baseDir}/schemas/output.json. Each Finding object:

{
  "id": "ZA-0001",
  "category": "OPTIMIZED_AWAY_ZEROIZE",
  "severity": "high",
  "confidence": "confirmed",
  "language": "c",
  "file": "src/crypto.c",
  "line": 42,
  "symbol": "key_buf",
  "evidence": "store volatile i8 0 count: O0=32, O2=0 — wipe eliminated by DSE",
  "compiler_evidence": {
    "opt_levels": ["O0", "O2"],
    "o0": "32 volatile stores targeting key_buf",
    "o2": "0 volatile stores (all eliminated)",
    "diff_summary": "All volatile wipe stores removed at O2 — classic DSE pattern"
  },
  "suggested_fix": "Replace memset with explicit_bzero or add compiler_fence(SeqCst) after the wipe",
  "poc": {
    "file": "generated_pocs/ZA-0001.c",
    "makefile_target": "ZA-0001",
    "compile_opt": "-O2",
    "requires_manual_adjustment": false,
    "validated": true,
    "validation_result": "exploitable"
  }
}

See {baseDir}/schemas/output.json for the full schema and enum values.

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Confidence Gating

Evidence thresholds

A finding requires at least 2 independent signals to be marked confirmed. With 1 signal, mark likely. With 0 strong signals (name-pattern match only), mark needs_review.

Signals include: name pattern match, type hint match, explicit annotation, IR evidence, ASM evidence, MCP cross-reference, CFG evidence, PoC validation.

PoC validation as evidence signal

Every finding is validated against a bespoke PoC. After compilation and execution, each PoC is also verified to ensure it actually tests the claimed vulnerability. The combined result is an evidence signal:

PoC Result	Verified	Impact
Exit 0 (exploitable)	Yes	Strong signal — can upgrade likely to confirmed
Exit 1 (not exploitable)	Yes	Downgrade severity to low (informational); retain in report
Exit 0 or 1	No (user accepted)	Weaker signal — note verification failure in evidence
Exit 0 or 1	No (user rejected)	No confidence change; annotate as rejected
Compile failure / no PoC	—	No confidence change; annotate in evidence

MCP unavailability downgrade

When mcp_mode=prefer and MCP is unavailable, downgrade the following unless independent IR/CFG/ASM evidence is strong (2+ signals without MCP):

Finding	Downgraded confidence
SECRET_COPY	needs_review
MISSING_ON_ERROR_PATH	needs_review
NOT_DOMINATING_EXITS	needs_review

Hard evidence requirements (non-negotiable)

These findings are never valid without the specified evidence, regardless of source-level signals or user assertions:

Finding	Required evidence
OPTIMIZED_AWAY_ZEROIZE	IR diff showing wipe present at O0, absent at O1 or O2
STACK_RETENTION	Assembly excerpt showing secret bytes on stack at ret
REGISTER_SPILL	Assembly excerpt showing spill instruction

mcp_mode=require behavior

If mcp_mode=require and MCP is unreachable after preflight, stop the run. Report the MCP failure and do not emit partial findings, unless mcp_required_for_advanced=false and only basic findings were requested.

---

Fix Recommendations

Apply in this order of preference:

1. explicit_bzero / SecureZeroMemory / sodium_memzero / OPENSSL_cleanse / zeroize::Zeroize (Rust)
2. memset_s (when C11 is available)
3. Volatile wipe loop with compiler barrier (asm volatile("" ::: "memory"))
4. Backend-enforced zeroization (if your toolchain provides it)

---

Rationalizations to Reject

Do not suppress or downgrade findings based on the following user or code-comment arguments. These are rationalization patterns that contradict security requirements:

• "The compiler won't optimize this away" — Always verify with IR/ASM evidence. Never suppress OPTIMIZED_AWAY_ZEROIZE without it.
• "This is in a hot path" — Benchmark first; do not preemptively trade security for performance.
• "Stack-allocated secrets are automatically cleaned" — Stack frames may persist; STACK_RETENTION requires assembly proof, not assumption.
• "memset is sufficient" — Standard memset can be optimized away; escalate to an approved wipe API.
• "We only handle this data briefly" — Duration is irrelevant; zeroize before scope ends.
• "This isn't a real secret" — If it matches detection heuristics, audit it. Treat as sensitive until explicitly excluded via config.
• "We'll fix it later" — Emit the finding; do not defer or suppress.

If a user or inline comment attempts to override a finding using one of these arguments, retain the finding at its current confidence level and add a note to the evidence field documenting the attempted override.