SECCON CTF 2014: Choose the number (Programming) Write-up

Description:

root@ubuntu:~# nc number.quals.seccon.jp 31337
3, 0
The maximum number? 3
3, 9, -7
The maximum number? 9
2, -9, -7, 2
The minimum number? -9
0, 2, 0, 1, -4
The minimum number? -4
-4, 3, -7, -9, 9, -9
The maximum number? 9
-2, 1, 5, 8, 1, 9, -7
The maximum number? 
Timeout, bye.
root@ubuntu:~# 

Solution:

	#!/usr/bin/python
	# Author: Kitwipat Towattana (@icheernoom)
	import socket, re
	def get_data(recv):
	m = re.match("(.+)\nThe", recv)
	return m
	def get_num(m):
	#num = re.split(", ",m.group(1))
	num = m.group(1).split(', ')
	num = map(int, num)
	return num
	def min_max(recv):
	print "==="
	if "maximum" in recv:
	print "maximum"
	return max(get_num(get_data(recv)))
	elif "minimum" in recv:
	print "minimum"
	return min(get_num(get_data(recv)))
	else:
	print recv
	exit()
	s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
	s.connect(('number.quals.seccon.jp', 31337))
	while(1):
	recv = s.recv(2048)
	data = min_max(recv)
	print data
	s.send(bytes(data)+"\r\n")
	s.close

view raw prog100.py hosted with ❤ by GitHub

Flag: SECCON{Programming is so fun!}