Lucid is an educational fuzzing project which aims to create a Bochs emulator based snapshot fuzzer capable of fuzzing traditionally hard to fuzz targets such as kernels and browsers.

Lucid is based on a fuzzer originally conceived of and developed by Brandon Falk.

Lucid utilizes changes to Musl in order to affect Bochs’ behavior and achieve a functional sandbox that will allow Lucid to run Bochs within its virtual address space without being able to interact directly with the operating system.

The goal of the sandbox is to achieve determinism.

Under Development

Lucid is currently in the early stages of development and can load and run a -static-pie test program as well as Bochs itself.

Lucid is also capable of sandboxing the test program from syscalls and access to thread-local-storage. More sandboxing work is required.

You can catch up on development efforts on the blog detailing each development step: The current codebase is more current than the latest blogpost.



Building the Rust portions of the project is very straightfoward, you should just be able to:

git clone

cd Lucid

cargo build --release


Lucid requires Musl libc 1.2.4, modified with Lucid-specific patches. Download and extract Musl:

tar -xzf musl-1.2.4.tar.gz

Apply Lucid patches to Musl:

cd path/to/musl-1.2.4

patch -p1 < path/to/musl_patches/musl.patch

Build and install the customized Musl:



sudo make install

Test Application

Confirm that Musl is now installed at /usr/local/musl, then you can:

gcc --specs=/path/to/musl_specs/musl-gcc.specs test.c -o test -g --static-pie


./lucid --bochs-image /path/to/test (--bochs-args)

Expected Output

lucid· Bochs image path: 'test'
lucid· Loading Bochs...
lucid· Bochs mapping: 0x10000 - 0x18000
lucid· Bochs mapping size: 0x8000
lucid· Bochs stack: 0x7F906B7FD000
lucid· Bochs entry: 0x11058
lucid· Creating Bochs execution context...
lucid· Starting Bochs...
       Argument count: 1
       Test alive!
       Test alive!
       Test alive!
       Test alive!
       Test alive!
       g_lucid_ctx: 0x55a26ef9fce0
fatal: Bochs exited early