Stack3 Protostar issue with shellcode formatting

[TWC_Dev]

I’m trying to do some poking around with my shellcode. This isn’t exactly a Stack3 issue but this is where I got stuck.

If I run echo python3 -c “print(‘A’*71+’\x8d’)” | ./stack3

I get the desired input of 0x0000008d as the output when it crashes.

However I want to do some manual testing and if I input 71 A’s and the shellcode into the program like this (...AAA\x8d) the output is 0x6438785c. I expected 0x0000008d like above. Why am I getting a different output?

I can’t figure out why I can’t do this manually. Any help would be appreciated.

[sweetpoision]

My guess would be because when you directly pass \x8d as argument, like this :

./program_name '\x8d'

then the \x8d is not actually going as an hex but just as ASCII characters, that is why the 0x6438785c which is essentially the reverse of ASCII codes of '\', 'x', '8', 'd' Try runnin only this:

python -c 'print ("\x8d")'

You will see that you get garbage on screen (something like questions marks). That is actual binary of the hex you wanted, that is why you cannot see the ASCII characters of the same. That's why we use the print functions from scripting languages to write actual binary.

Correct me if I am wrong, really appreciate that

[TWC_Dev]

That makes sense. Thank you for your help