SC1: Math bot
100
It is well known that computers can do tedious math faster than human.
nc 195.154.53.62 1337
Update we got another mirror here
nc 195.154.53.62 7331
When talking to the remote bot system we see that it gives us a number of simple expressions to solve:
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$ nc 195.154.53.62 1337
__________
______/ ________ \______
_/ ____________ \_
_/____________ ____________\_
/ ___________ \ / ___________ \
/ /XXXXXXXXXXX\ \/ /XXXXXXXXXXX\ \
/ /############/ \############\ \
| \XXXXXXXXXXX/ _ _ \XXXXXXXXXXX/ |
__|\_____ ___ // \\ ___ _____/|__
[_ \ \ X X / / _]
__| \ \ / / |__
[____ \ \ \ ____________ / / / ____]
\ \ \ \/||.||.||.||.||\/ / / /
\_ \ \ ||.||.||.||.|| / / _/
\ \ ||.||.||.||.|| / /
\_ ||_||_||_||_|| _/
\ ........ /
\________________/
Our system system has detected human traffic from your IP!
Please prove you are a bot
Question 1 :
202442497028903948486871061450208 % 191074133703182836787330064501304 =
11368363325721111699540996948904
Question 2 :
306327109688119887963854945995024 % 289503955876579516432389611624816 =
16823153811540371531465334370208
...
There are too many of them to solve by hand however, so we will use Python’s eval() function to complete them:
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from pwn import *
r = remote('195.154.53.62', 1337)
r.recvline_contains('Please prove you are a bot')
while True:
s = r.recvline(False)
print s
if s.endswith('='):
answer = str(eval(s[:-1]))
print answer
r.sendline(answer)
Running the script gives us the key ALEXCTF{1_4M_l33t_b0t}:
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$ python solve.py
...
Question 250 :
221674459966639462312539617249524 + 199262348569153796979171354903174 =
420936808535793259291710972152698
Well no human got time to solve 500 ridiculous math challenges
Congrats MR bot!
Tell your human operator flag is: ALEXCTF{1_4M_l33t_b0t}