Write zeros in memory through a buffer overflow

Question

Trying to give a command line program an address to overwrite a return address saved in the stack. I could successfully overflow the input argument into the exact return address position but the address I want to give contains zeros (starts with with zeros eg 0x0000555555554bce).

I give the address in from of string, the 00 must be a NUL character (\0) but I can't give that using the command line. Any idea on how can I achieve that?

Answer 1

If I understood correctly the problem has to do with packing your input. You can use any scripting language to pack your input. For example in python you can do (assuming x64-bit arch):

cat <(python -c 'from pwn import p64; print your_padding_here + p64(0x555555554bce)') - | ./your_program

or if for any reason you prefer only built-in modules:

cat <(python -c 'print your_padding_here + __import__("struct").pack("I", 0x555555554bce)') - | ./your_program

Also you can accomplish the same thing by writing the buffer to a file and then pass the file as input.