What it does. 'Performs coverage-guided fuzzing of compiled binaries with AFL++, instrumenting Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill performing-fuzzing-with-aflplusplus, or copy the skill folder into ~/.claude/skills/performing-fuzzing-with-aflplusplus/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/performing-fuzzing-with-aflplusplus/SKILL.md

SKILL.md (verbatim)

name: performing-fuzzing-with-aflplusplus
description: 'Performs coverage-guided fuzzing of compiled binaries with AFL++, instrumenting
  targets via afl-cc/afl-clang-fast, minimizing corpora with afl-cmin and afl-tmin,
  running parallel campaigns with afl-fuzz, and triaging crashes with CASR or GDB
  scripts. Use for binary fuzzing, crash and memory-corruption discovery, coverage-guided
  testing, or running AFL++ fuzzing campaigns.

  '
domain: cybersecurity
subdomain: application-security
tags:
- fuzzing
- aflplusplus
- coverage-guided
- crash-triage
- binary-analysis
- security-testing
version: '1.0'
author: mahipal
license: Apache-2.0
nist_ai_rmf:
- MEASURE-2.7
- MAP-5.1
- MANAGE-2.4
atlas_techniques:
- AML.T0070
- AML.T0066
- AML.T0082
nist_csf:
- PR.PS-01
- PR.PS-04
- ID.RA-01
- PR.DS-10
mitre_attack:
- T1078
- T1190
- T1059
- T1005

Performing Fuzzing with AFL++

Overview

AFL++ is a community-maintained fork of American Fuzzy Lop (AFL) that provides coverage-guided fuzzing for compiled binaries. It instruments targets at compile time or via QEMU/Unicorn mode for binary-only fuzzing, then mutates input corpora to discover new code paths. AFL++ includes advanced scheduling (MOpt, rare), custom mutators, CMPLOG for input-to-state comparison solving, and persistent mode for high-throughput fuzzing.

When to Use

• When conducting security assessments that involve performing fuzzing with aflplusplus
• When following incident response procedures for related security events
• When performing scheduled security testing or auditing activities
• When validating security controls through hands-on testing

Prerequisites

• AFL++ installed (apt install afl++ or build from source)
• Target binary source code (for compile-time instrumentation) or QEMU mode for binary-only
• Initial seed corpus of valid inputs for the target format
• Linux system with /proc/sys/kernel/core_pattern configured

Steps

1. Instrument the target binary with afl-cc or afl-clang-fast
2. Prepare seed corpus directory with minimal valid inputs
3. Minimize corpus with afl-cmin to remove redundant seeds
4. Run afl-fuzz with appropriate flags (-i input -o output)
5. Monitor fuzzing progress via afl-whatsup and UI stats
6. Triage crashes with afl-tmin minimization and CASR/GDB analysis
7. Report unique crashes with reproduction steps

Expected Output

+++ Findings +++
  unique crashes: 12
  unique hangs: 3
  last crash: 00:02:15 ago
+++ Coverage +++
  map density: 4.23% / 8.41%
  paths found: 1847
  exec speed: 2145/sec

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

AFL++ Fuzzing — API Reference

Installation

apt install afl++                    # Ubuntu/Debian
# Or build from source:
git clone https://github.com/AFLplusplus/AFLplusplus && cd AFLplusplus && make all

AFL++ CLI Tools

afl-fuzz Key Flags

fuzzer_stats File Fields

Crash Triage Tools

External References

• AFL++ Documentation
• AFL++ GitHub
• CASR Crash Triage

Back to mukul975/Anthropic-Cybersecurity-Skills (817 security skills) or Agent skills.