LibAFL, the fuzzer library


Advanced Fuzzing Library - Slot your own fuzzers together and extend their features using Rust.

LibAFL is written and maintained by Andrea Fioraldi [email protected] and Dominik Maier [email protected]

LibAFL is a collection of reusable pieces of fuzzers, written in Rust. It is fast, multi-platform, no_std compatible, and scales over cores and machines.

It offers a main crate that provide building blocks for custom fuzzers, libafl, a library containing common code that can be used for targets instrumentation, libafl_targets, and a library providing facilities to wrap compilers, libafl_cc.

LibAFL offers integrations with popular instrumentation frameworks. At the moment, the supported backends are:

  • SanitizerCoverage, in libafl_targets
  • Frida, in libafl_frida, by s1341 [email protected]
  • QEMU user-mode, in libafl_qemu

Features

LibAFL gives you many of the benefits of an off-the-shelf fuzzer, while being completely customizable. Some highlight features currently include:
fast: We do everything we can at compile time, keeping runtime overhead minimal. Users reach 120k execs/sec in frida-mode on a phone (using all cores).
scalable: Low Level Message Passing, LLMP for short, allows LibAFL to scale almost linearly over cores, and via TCP to multiple machines.
adaptable: You can replace each part of LibAFL. For example, BytesInput is just one potential form input: feel free to add an AST-based input for structured fuzzing, and more.
multi platform: LibAFL was confirmed to work on Windows, MacOS, Linux, and Android on x86_64 and aarch64. LibAFL can be built in no_std mode to inject LibAFL into obscure targets like embedded devices and hypervisors.
bring your own target: We support binary-only modes, like Frida-Mode, as well as multiple compilation passes for sourced-based instrumentation. Of course it's easy to add custom instrumentation backends.

Installation Process

  1. Install the Rust development language. We highly recommend not to use e.g. your Linux distribution package as this is likely outdated. So rather install Rust directly, instructions can be found here.
  2. Clone the LibAFL repository with
  3. git clone https://github.com/AFLplusplus/LibAFL
  4. Build the library using
    cargo build --release
  5. Build the API documentation with
    cargo doc 
  6. Browse the LibAFL book (WIP!) with (requires mdbook)
  7. cd docs && mdbook serve
It collects all example fuzzers in ./fuzzers. Be sure to read their documentation (and source), this is the natural way to get started!
The best-tested fuzzer is ./fuzzers/libfuzzer_libpng, a multicore libfuzzer-like fuzzer using LibAFL for a libpng harness.