text: Y-Not-CTF - MadCow
  The binary ask for an input and do a ton of computation on it. solved using an angr script.
  Description
  Take your time to solve this one until the end of the CTF…
  Details
  Points: 474
  Category: reverse
  Validations: 4
  Solution
  We were given a file called MadCow_3ad6db829e62619f19a299086c0f22cf94b36903.
  After launching the file a nice cow in ascii art was shown.
  / \ ((__-^^-,-^^-__)) `-_---' `---_-' <__|o` 'o|__> \ ` / ): :( :o_o: "-" 03:19:05 remaining, take your time!!! what Nope, Try again!
  Opening the file in ida pro shown a mess of calculation on the input.
  It seems that is a nice candidate for angr.
  We wrote a simple python script to bruteforce the flag.
  import angr, simuvex, logging logging.basicConfig(level=logging.DEBUG) p = angr.Project('./MadCow_3ad6db829e62619f19a299086c0f22cf94b36903', load_options={'auto_load_libs': False}) ex = p.surveyors.Explorer(find=(0x0401C4D, ),avoid=(0x0401C54,)) res = ex.run() for i in res.found: print i.state.posix.dumps(0)
  Running the script for 10 seconds give us the flag: YNOT17{4ngR_1ntr0duCt10n}.
  Challenges resources are available in the resources folder
  Written on November 17, 2017