A repo of binary packing stuff
My first packer is an ELF binary packer based off of elfinject.c in the bookk Practical Binary Analysis.
The technique revolves around appending executable code to the end of a target binary, and the modifying a PT_NOTE program header and SHT_NOTE section to directly reference this newly added code section.
These two sections are changed to executable program and section headers respectively; the first PT_NOTE section is overwritten and changed to a PT_LOAD section and has its address and offset point to my newly injected code, and the SHT_NOTE section is changed to a SHT_PROGBITS section also pointing to my injected code.
Lastly, the entrypoint of the program in the program header is changed to point to the address of my injected code so it jumps here on program startup.