0ld is g0ld

Description: Old algorithms are not a waste, but are really precious…

This challenge is rather easy and straightforward. The first thing to do is of course to download the file and unzip it with the given password hackthebox:

The file is a PDF, and we can open it with the command xdg-open as follows:

The file is protected by a password. So, let’s look on the internet if there is any tool to crack it. We quickly find the tool pdfcrack. I had an error when installing it, so I had to update first:

Then, pdfcrack was installed successfully. The command pdfcrack shows the available options. I first tried to use pdfcrack without giving it any wordlist, but stoppd it after ~20 minutes because my CPU was heating too much. I then tried with the common rockyou file and got something:

We should now be able to open the PDF. For some reason, I couldn’t open the file on Kali and used my Mac instead. Here is the content:

I have no clue who this person is. At the bottom of the page, there is something else:

This strongly looks like Morse code, so we can check this assumption with any online tool (just type morse code translator). It returned “R1PSAMU3LM0RS3” (RIP Samuel Morse). It makes sense, the picture was in fact Samuel Morse! And this is also the flag for this challenge.