PDFCrack - Password Cracking Tool for PDF-files

PDFcrack is a GNU/Linux tool for cracking password protected PDF files. It is a very small command line application. It is not preinstalled in kali linux. We can install through command line.

For installing pdfcrack

open a terminal and enter apt install pdfcrack

Syntax and options

Usage: pdfcrack -f filename [OPTIONS]

          : pdfcrack -f filenmae -w passwordfile.txt

OPTIONS:

-b, --bench perform benchmark and exit

-c, --charset=STRING Use the characters in STRING as charset

-w, --wordlist=FILE Use FILE as source of passwords to try

-n, --minpw=INTEGER Skip trying passwords shorter than this

-m, --maxpw=INTEGER Stop when reaching this passwordlength

-l, --loadState=FILE Continue from the state saved in FILENAME

-o, --owner Work with the ownerpassword

-u, --user Work with the userpassword (default)

-p, --password=STRING Give userpassword to speed up breaking

ownerpassword (implies -o)

-q, --quiet Run quietly

-s, --permutate Try permutating the passwords (currently only

supports switching first character to uppercase)

-v, --version Print version and exit

The key in cracking a password protected file is the strength of the password list file we use for cracking. The more powerful the wordlist the more likely the password to be cracked. 

Example:

I am going to crack a password protected pdf file

syntax is

pdfcrack -f pdfcrack.pdf -w pass.txt

here pdfcrack .pdf is the filename and pass.txt is the password list file.

 

Result:

pdfcrack found out the password “hello”. We can now open the file using the password.