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Red Team Village Defcon 2020 CTF - Seeding
#!/usr/bin/env python3
import socket
import threading
import random
import string
import socket
import sys
import logging
from datetime import datetime
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',
datefmt='%m-%d %H:%M',
filename='seedthing.log',
filemode='a')
if len(sys.argv) < 2:
logging.debug("ALERT: Using default port 3000 since one wasnt provided.")
logging.debug("EXAMPLE: You can do for example '%s 3050' to change the port if you'd like." % sys.argv[0])
port = 3000
else:
port = sys.argv[1]
try:
port = int(port)
except ValueError:
logging.debug("ERROR: Must provide an integer between 1 and 65535.")
exit(0)
if port > 65535 or port < 1:
logging.debug("ERROR: Must provide an integer between 1 and 65535.")
exit(0)
def start_seed(max):
random.seed(datetime.now())
seed = random.randint(1,max)
random.seed(seed)
return seed
def get_random_string(length):
key = 'ereselamordemivida'
result_str = ''.join(random.choice(key) for i in range(length))
return result_str
def get_x_iteration(x):
for i in range (0,x):
if i == x-1:
return get_random_string(16)
get_random_string(16)
class ThreadedServer(object):
def __init__(self, host, port):
self.host = host
self.port = port
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.sock.bind((self.host, self.port))
def listen(self):
self.sock.listen(5)
while True:
client, address = self.sock.accept()
client.settimeout(5)
threading.Thread(target = self.listenToClient,args = (client,address)).start()
def listenToClient(self, client, address):
size = 1024
while True:
try:
host, port = client.getpeername()
max = 100
seed = start_seed(max)
fourth = get_x_iteration(4)
leet = get_x_iteration((1337-4))
data = b"The seed is a number that can be from anywhere between 1 to %s.\n" % str.encode(str(max))
data += b"The seed this run was: %s\n" % str.encode(str(seed))
data += b"The fourth iteration of this key is: %s\n" % str.encode(fourth)
data += b"\n"
data += b"The first flag is the key. What is the key?: "
client.send(data)
data = client.recv(size)
try:
data = data.decode('utf-8').strip('\r').strip('\n')
except:
data = data.strip('\r').strip('\n')
logging.debug(b"RECEIVED KEY FROM %s: " % str.encode(str(host)) + str.encode(data))
if data == 'ereselamordemivida':
logging.debug(b"VALID KEY FROM %s: " % str.encode(str(host)) + str.encode(str(data)))
response = b"Correct! Heres the flag flag{YouCanBruteForceAnything}\nMoving to next piece...\n"
client.send(response)
data = b"\nThe 1337th iteration of using the seed to randomize the key during runtime is the password.\n"
data += b"Please enter it to continue: "
client.send(data)
data = client.recv(size)
try:
data = data.decode('utf-8').strip('\r').strip('\n')
except:
data = data.strip('\r').strip('\n')
logging.debug(b"RECEIVED FINAL ANSWER FROM %s: %s" % (str.encode(str(host)), str.encode(data)))
if data == leet:
logging.debug(b"CORRECT FINAL ANSWER FROM %s: %s" % (str.encode(str(host)), str.encode(data)))
data = b"Congratulations!!! Heres the last flag{IsthisCrypto?}\n"
client.send(data)
client.close()
else:
data = b"You're so close...try again!\n\n"
client.send(data)
logging.debug(b"INCORRECT FINAL ANSWER FROM %s: %s" % (str.encode(str(host)), str.encode(data)))
elif data:
logging.debug(b"INVALID KEY FROM %s: " % str.encode(str(host)) + str.encode(data))
response = b"You entered %s..." % str.encode(data)
response += b"This is incorrect, try again...\n\n"
client.send(response)
else:
raise error('Client disconnected')
except Exception as e:
logging.debug(e)
logging.debug("Error on line {}".format(sys.exc_info()[-1].tb_lineno))
client.close()
return False
if __name__ == "__main__":
while True:
port_num = port
try:
port_num = int(port_num)
break
except ValueError:
pass
logging.debug("Starting server on port: %s" % port_num)
ThreadedServer('',port_num).listen()
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