Skip to content
TrustedSkillsbeta
Back to all skills

Libfuzzer

Listed
trailofbits·vlatest·security·CC-BY-SA-4.0

Libfuzzer automatically discovers vulnerabilities in software by mutating binaries and running them against a target, boosting security testing efficiency.

Repository

Install on your platform

Showing Claude Code. One command installs this skill into any of the agents below.

  1. 1

    Run this in your project

    terminal
    $ npx skills add trailofbits/skills --skill libfuzzer -a claude-code

  2. Uses the open-source skills CLI and needs Node.js. Add -g to install it for your user instead of this project.

What we know about this skill

Publisher

trailofbits

Taken from the source listing. We haven't verified who controls this account.

Install target

Live repository

Not pinned. Installing fetches whatever the repository holds at the time you run the command.

No human has reviewed this code. The checks below are a static scan of the files at one commit — nobody has run this skill or judged whether it works. A skill runs with whatever access you give your agent, so read the source before you install it.

Automated safety checks

scanned

This skill failed 1 of 6 checks. A failure is not proof of bad intent; it means something in the code needs a human to look at it before you run it.

  • No undeclared network calls: failed

    Contacts 1 host that is neither well-known infrastructure nor declared in the skill's frontmatter: downloads.sourceforge.net.

    Every host the skill dials — from its scripts, its config endpoints or the commands it tells the agent to run — is either well-known package and API infrastructure or declared in its own frontmatter. Links in documentation are not counted.

    Hosts contacted

    downloads.sourceforge.netundeclaredraw.githubusercontent.comsource host

    What it found

    • plugins/testing-handbook-skills/skills/libfuzzer/SKILL.md:612contacts downloads.sourceforge.net
      curl -L -O https://downloads.sourceforge.net/project/libpng/libpng16/1.6.37/libpng-1.6.37.tar.xz

  • Declares what it does: passed

    SKILL.md parses and declares a name and a description.

    SKILL.md exists, its frontmatter parses, and it declares a name and a description.

  • No obfuscated payloads: passed

    No encoded or obfuscated payloads.

    No base64, hex or compressed blob is decoded and then executed, and no encoded shell commands.

  • No credential access: passed

    Reads no keys, tokens, keychains or credential files.

    Neither the code nor the SKILL.md instructions read SSH keys, cloud credentials, keychains, token stores, browser cookie databases or dotfiles that hold secrets.

  • No pipe-to-shell installers: passed

    No pipe-to-shell or download-and-run installers.

    No `curl … | sh` pattern, in the code or in the instructions, that runs code fetched at run time.

  • Pinned to a commit: passed

    Scanned trailofbits/skills at 82fe822625.

    The exact upstream commit SHA that was scanned is recorded, so the result refers to specific bytes.

Commit
82fe822625
Manifest
plugins/testing-handbook-skills/skills/libfuzzer/SKILL.md
Scanned
2 files, 685 lines
This is a static scan, not a review. It reads the skill's files; it does not run them, and it cannot tell you whether the skill is any good or whether the code does what its description says. A skill runs with whatever access you give your agent.
What each check looks for →

About this skill

What it does

libfuzzer is a powerful fuzzer that helps find security vulnerabilities in software by generating random, invalid inputs and observing the program's behavior. It’s particularly effective for discovering crashes and other unexpected errors that can be exploited. This skill allows AI agents to leverage libfuzzer for automated vulnerability discovery within codebases.

When to use it

  • Security Audits: Integrate into security audit workflows to proactively identify vulnerabilities before deployment.
  • Regression Testing: Run fuzzing tests after code changes to ensure new features haven't introduced regressions or unexpected behavior.
  • Automated Vulnerability Research: Automate the process of finding and classifying software bugs by continuously fuzzing target applications.
  • Code Coverage Analysis: Use libfuzzer to increase code coverage during testing, revealing areas that might be missed by traditional tests.

Key capabilities

  • Coverage-guided fuzzing: libfuzzer uses feedback from the program's execution to guide its input generation.
  • Crash reporting: Automatically reports crashes and generates minimal reproduction cases.
  • Integration with debuggers: Allows for detailed debugging of crashes.
  • Support for various data types: Handles a wide range of input formats, including binary files and network protocols.

Example prompts

  • "Fuzz the image_parser module in this repository."
  • "Run libfuzzer on the network_protocol_handler with these seed inputs."
  • "Generate a report detailing crashes found while fuzzing the audio_decoder."

Tips & gotchas

  • Requires access to source code and build environment for the target application.
  • Fuzzing can be computationally intensive, requiring significant processing power and time.