Get the latest tech news
A whirlwind tutorial on creating teensy ELF executables for Linux (1999)
She studied it carefully for about 15 minutes. Finally, she spoke.
For example, the first sixteen bytes contain an "identifier", which includes the file's magic-number signature (7F 45 4C 46), and some one-byte flags indicating that the contents are 32-bit or 64-bit, little-endian or big-endian, etc. This field is mainly used when relocating segments containing position-independent code (as for shared libraries), so for an executable file Linux will ignore whatever garbage we store here. Since we can't change the p_flags field without moving the program header table out of alignment, you might think that the only solution would be to lower the p_memsz value back down to equal p_filesz (which would make it impossible to share it with e_entry).
Or read this on Hacker News