This is part of my write up from the Hackfu 2015 Security Challenge.

The third and last challenge I solved was surprisingly very easy, but there might have been more to it...

The instructions given were:

An ELF Binary file: shipbinary

"Your mission is to analyse the executable binary and find a way to get it to run to its completion so that it ends up spitting out the access code for the ship's central server."

Below is how I solved that challenge:
We first run the following command to see all the printable/ASCII strings from the binary.
> strings shipbinary
Below is an extract of the most interesting result from the above command.
Enter Decryption Code:
burnthelandandboilthesea
Code Accepted.
Establishing Connection to Planet Abaddon...
out.txt
123.123.123.1 -c 1 | tail -1| awk '{print $4}' | cut -d '/' -f 2
ping %s > %s
No Response From Homebase...
Connection Established!
Decrypting Password

The passcode “burnthelandandboilthesea” is the password for the encrypted file and the solution for this challenge!
What!? Wait a minute! I thought the instructions were to get the program to run to completion... plus this is far too simple!
Anyway, this is was apparently all you needed to get the points for this challenge!
The end? Well no, let's try to complete the challenge as I think it should have been solved, let get that program to complete!

As per the text strings extract above, the binary tries to ping the IP 123.123.123.1
So you need to setup your computer to respond to that ping to see what happens when you run the binary (after doing a chmod +x shipbinary).
I edited /etc/network/interface and added the following lines:

auto eth0:1
allow-hotplug eth0
iface eth0 inet static
address 123.123.123.1
netmask 255.255.255.0

Save it
restart the network interface:
> sudo /etc/init.d/networking restart

This creates a new virtual interface with the IP address of 123.123.123.1

Running the binary and using the “burnthelandandboilthesea” passcode now let us proceed and a password is given as per the binary logs below:
---
$ ./shipbinary
Enter Decryption Code:
Code Accepted.
Establishing Connection to Planet Abaddon...
Connection Established!
Decrypting Password
[==============>]
Pasword Decrypted
Password: 103171102274726
---

Not sure what this password is for! But we got the program to run!