Brute force a PDF with pdfcrack

I recently forgot the 4 digit pin to my payslips and decided to brute force my way in – because sending an email to finance and asking for it is too much of a hassle 😉

I came across a tool called pdfcrack and it’s as simple as:

Install pdfcrack

Then specifying the required flags:

Run it against your file – while specifying the minimum (-n) and maximum (-m) number of characters

I knew my pin was only 4 characters and it cracked it in milliseconds. If you want to know more about the tool be sure to use the ‘man pdfcrack’ or ‘pdfcrack –help’ options.

Reference:

Bruteforce password protected PDF