Description:
#Hope #Change #Obama2008
nc misc.chal.csaw.io 8000
Let’s connect to the server and see what will happen:
[Megabeets] /tmp/CSAW/Coinslot# nc misc.chal.csaw.io 8000
$0.07
$10,000 bills: 0
$5,000 bills: 0
$1,000 bills: 0
$500 bills: 0
$100 bills: 0
...
...
So, the server is displaying a wanted amount of money and we need to calculate the number of bills and coins given the amount. All we need is writing a simple python script and a coffee break because it will take about 10 minutes for the flag to come up 🙁
from pwn import *
r = remote('misc.chal.csaw.io',8000)
# Create an array of dollars and coins values
money = [10000.0, 5000.0, 1000.0, 500.0, 100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 0.5, 0.25, 0.1, 0.05, 0.01]
count = 0
while(True):
count += 1
amount = 0.0
# Recieve the wanted amount of money
amount = float(r.recvline()[1:])
print "Wanted amount is " + str(amount)
# Send the number of dollars and coins for each value
for m in money:
print r.recv()
ans = int(amount/m)
print "Sending %d" %ans
r.sendline(str(ans))
amount = round((amount - (ans*m)), 2)
print "Left with " + str(amount)
print "[+] Finished %d" %count
print r.recvline()
The flag is:_ flag{started-from-the-bottom-now-my-whole-team-fucking-here}_
Eat Veggies
