GrabBag 100 was this CTF’s loss leader and an easy one if you are familiar with the legendary Hackers movie from 1995 starring Jonny Lee Miller, Angelina Jolie and Jesse Bradford. The assignment read:
We need your help to hack the planet!!! Somehow we have lost a little chunck of the garbage file. We just need 4 byte starting from address
0x000020. Please help us!!!(Hint: in hex, lowercase,without leading 0x)
To solve the challenge just grab your old copy of Hackers you’re still hiding somewhere, power up the VHS recorder and forward to the scene were Cereal Killer opens Plague’s garbage file. The file gets hexdumped for a blink of an eye, here’s a shot:
hexdumping the garbage file
Starting from 0x20 we read four bytes as advised: 3dc6032c was the flag.
Never send a boy to do a woman’s job. (Kate)