infect.s

a basic x86 elf file infector written in pure x86 assembly, using the Segment padding infection thechnique along with finding in-segment null-byte blocks

assembling commands

first you want to . asmrc or append the content of that file to your ~/.bashrc or ~/.zshrc or whatever file your shell uses

then build the infector executable using

asm infect.s

and the payload file using

asm elf.s

requirements

there are 2 requirements for the payload, to be postion independent, and to contain a DWORD value of 0x69696969 inside of it, or else the infection won't happen

now the payload doesn't have to be null-byte-free but that's preferable as it helps to generate a smaller code, refer to elf.s to get an idea of what an accepted payload should look like

quick demo

note : the payload segfaults because it's trying to return to 0x69696969 which is not a valid address

todo list

document the undocumented routines
rename elf.s to payload.s and apply the change to the readme file and the gif
make a better demo.gif
~~optimize~~ keep optimizing the original infecter
write a 64 version
figure out a way to make it support both 32 and 64 elf files without writing every routine twice
make it position indepedent then get rid of the null bytes (probably won't do this one)

any contribution would be much appreciated, tho it's preferable to be either an optimization of the already existed code or some theory that might help me add new features

a special thanks

to pico (0x00pf) for his original write up on elf file infection