The challenge's description :
Netcatting the given address and port we discover an app:
We get some sort of random string everytime and we have limited time to input a " work proof " as the screenshot indicates.
If we spend more than 10 seconds the session is aborted.
eJwrzy_Kji8oys9Ps000Lc7MSM1IS6syTc1ITTVJTjVLSTFJM6zKMEwysSzPAABseg_F
Looking at the string, i was unable to identify it's nature so i tried hashid
After playing with it for a little while, i decoded it from base64 and to Hex using Cyberchef :
zebra-lib ? maybe it's a hint to z-lib ?
78 9c is for sure the z-lib header.
Passing our proof of work to the server we get another one :
Usually, it takes more than one or two iterations to solve a proof of work so it won't do us any good doing that manually. =======> Python
from pwn import *
import zlib
from base64 import *
conn = remote('34.159.7.96',30441 )
i = 0
while True:
i+=1
print(conn.recvline())
a = conn.recvline()
print(a)
hashy = a.decode("utf-8").replace("\r\n","")
print(hashy)
print(hashy)
decoded = urlsafe_b64decode(hashy)
proof = zlib.decompress(decoded)
print(proof)
conn.sendline(proof)
print(conn.recvline())
conn.close()
It took us 500 iterations to get the flag weeeeeeeeeee
Made By Fckroun <3