Convert standard elf files to standalone shellcodes. Please read the following documentation and view the examples for this project to work properly
- mips
- i386 (intel x32)
- x86_64 (intel x64)
- arm (32bit)
- aarch64 (arm 64 bit)
- RISC-V rv64
pip install py_shelf- python3
The python library parses the elf and create a simple relocatable file format called shelf (shellcode elf).
The mini loader is inserted as the entry point for shelf.
the mini loader will load and relocate the shelf then it will execute it. There are no special requirements, the library contain the compiled mini loaders and resources.
The diagram below explain the format (Only work in browsers)
classDiagram
ShellcodeEntryPoint --|> MiniLoader
ShellcodeEntryPoint: Shellcode containing pre mini loader logic
MiniLoader --|> Relocation table
MiniLoader: Contain all the logic for parsing the relocation table
MiniLoader: fully os independent
Relocation table --|> HOOKS Optional
Relocation table : Contain table required for shellcode runtime relocation
HOOKS Optional --|> SHELF
HOOKS Optional: Read more about hooks in the documentation below
HOOKS Optional: This section is optional and only exists if hooks are used
SHELF: Shellcode elf - This is the compiled binary we convert into shellcode
SHELF: This binary is stripped into only opcodes
SHELF: fully relocatable using the relocation table
This project is intended to convert elf to os independent shellcodes. Therefor the loader never allocate memory and the shellcode format is not packed. You can just execute it, eg ...
((void (*)()) shellcode)();- note that __libc_start_main perform syscalls therefor if you want your shellcode to be fully os independent you must compile with -nostartfiles
- Shelf by default expects RWX (Read Write Execute) memory shelf can run in RX environments (Read Execute) Click the link to read more
follow the examples below
Some compilation flags are required for this to work properly. You must compile the binary with -fPIE and -static take a look at the provided examples below (makefile).
shellcode is a stripped binary with no symbols and no elf information only opcodes, in order to make the shellcode this library require a binary with elf information. so make sure you are not stripping the binary before using this library
simplified make command for mips big endian
gcc example.c -fno-stack-protector -fPIE -fpic -static -nostartfiles --entry=main -o binary.out
python -m shelf --input binary.out You can use the provided shellcode Loader to test you shellcodes
qemu-mips ./shellcode_loader ./myshellcode.outit is advised to use the shelf loader library to tests your shellcode here you can read more about it: Shelf loader documentation
for following links only work on the github page