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DEFCON CTF 2012 Grab bag 300
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#!/usr/bin/env python | |
from __future__ import with_statement | |
from contextlib import closing | |
from itertools import imap, ifilter | |
import socket, re | |
PW = '5fd78efc6620f6\n' | |
TARGET = ('140.197.217.85', 10435) | |
PROMPT = 'Enter ATM PIN:' | |
ESCAPE_RE = re.compile('\x1b\\[0;[0-9]+;[0-9]+m') | |
INTERESTING_RE = re.compile(' [0-9] ') | |
EXAMPLES = 3 | |
DIGITS = 4 | |
INIT_RANGE = range(36) | |
def main(): | |
with closing(socket.socket()) as s: | |
s.connect(TARGET) | |
s.send(PW) | |
while True: | |
buf = '' | |
while PROMPT not in buf: | |
r = s.recv(4096) | |
buf += r | |
if r: | |
print repr(r) | |
pin = buffer2pin(buf) | |
print 'PIN:', pin | |
s.send(pin + '\n') | |
def buffer2pin(buf): | |
buf = ESCAPE_RE.sub('', buf) | |
buf = filter(INTERESTING_RE.search, imap(str.strip, buf.split('\n'))) | |
sets = [set(INIT_RANGE) for _ in xrange(DIGITS)] | |
for i in xrange(EXAMPLES): | |
base = ''.join(buf[i * 7:i * 7 + 6]).replace(' ', '') | |
for n, i in enumerate(ifilter(str.isdigit, buf[i * 7 + 6])): | |
sets[n].intersection_update(m.start() for m in re.finditer(i, base)) | |
quest = ''.join(buf[3 * 7:3 * 7 + 6]).replace(' ', '') | |
return ' '.join(quest[digit.pop()] for digit in sets) | |
if __name__ == '__main__': | |
main() |
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