Use gdb script to solve OpenCTF 2016 neophyte_revsersing (linked from ctftime writeup)

neophyte_revsersing.gdbscript

b *0x080492a4
commands 1
    set $last_data = $eax
    call memcpy($tmp, $last_data, 0x14)
    continue
end

b *0x080492ad
commands 2
    call memcpy($last_data, $tmp, 0x14)
    set $argv = *(char***)($ebp+0xc)
    set $flag = $argv[1]
    set $i = *(int*)($esp+0x18)
    set $flag[$i] += 1
    x/s $flag
    set $eip = 0x0804927e
    continue
end

b *0x080492B5
commands 3
    x/s $flag
    continue
end

b *0x08049242
commands 4
    call malloc(0x14)
    set $tmp = $eax
    continue
end

run "                                         "

# vim: ft=gdb

OpenCTF2016 - neophyte_revsersing.md

Actually I solved this challenage with angr, but I tried to do this with gdb scripting after DEF CON.

Have fun :)

gdb ./neophyte_revsersing
source ./neophyte_revsersing.gdbscript
# wait for flag

Binary: https://github.com/ctfs/write-ups-2016/tree/master/open-ctf-2016/reversing/neophyte-reversing-200