Blowfish Password Cracking

G5 Cyber Security

1 week ago

TL;DR

This guide shows you how to crack a Blowfish-encrypted password using hashcat, a popular password cracking tool. It covers setting up hashcat, preparing your wordlist, and running the attack. Be aware that attempting to crack passwords without permission is illegal.

Prerequisites

Linux Environment: Hashcat works best on Linux (e.g., Ubuntu, Kali). Windows can be used with WSL.
Hashcat Installation: Download and install hashcat from https://hashcat.net/. Follow the instructions for your operating system.
Blowfish Hash: You need the Blowfish hash you want to crack. This is usually a string of characters generated by an encryption program.
Wordlist: A text file containing potential passwords (see Step 2).

Step-by-Step Guide

Verify Hashcat Installation
Open a terminal and run:
```
hashcat --version
```
This should display the hashcat version information. If it doesn’t, ensure hashcat is correctly installed and in your system’s PATH.
Prepare Your Wordlist
A good wordlist is crucial for success. You can:
- Use a pre-made list: Download common password lists from the internet (e.g., RockYou.txt). Be aware of their size!
- Generate your own: Use tools like cewl or crunch to create custom wordlists based on known information about the target. For example, using crunch:
```
crunch 8 16 -d @/usr/share/wordlists/rockyou.txt | head -n 100 > my_wordlist.txt
```
- Combine lists: Merge multiple wordlists to increase coverage.
Determine the Blowfish Hash Type
Hashcat needs to know the hash type. For standard Blowfish, it’s usually 3200. You can confirm this by searching online for your specific encryption program and its corresponding hash type.
Run the Attack with Hashcat
Use the following command to start cracking:
```
hashcat -m 3200 hash.txt my_wordlist.txt
```
- -m 3200: Specifies the Blowfish hash type.
- hash.txt: The file containing your Blowfish hash. Replace with the actual filename.
- my_wordlist.txt: The path to your wordlist. Replace with the actual filename.
Monitor Progress
Hashcat will display its progress in the terminal, showing the number of hashes cracked per second. It also shows estimated time remaining.
Check Results
If a password is found, Hashcat will output it to the terminal. It will also create a hashcat.potfile file containing the cracked passwords.
Using Rules (Optional)
Rules modify your wordlist by adding numbers, symbols, or capitalization variations. This can significantly increase your chances of success.
```
hashcat -m 3200 hash.txt my_wordlist.txt -r rules/best64.rule
```
- -r rules/best64.rule: Applies the ‘best64’ rule set to your wordlist. Hashcat includes many pre-defined rule sets in its rules/ directory.

Important Considerations

Hash Length and Complexity: Longer, more complex passwords are much harder to crack.
Wordlist Quality: The quality of your wordlist is the most important factor.
Hardware: Hashcat benefits greatly from powerful GPUs.
Legal Implications: Cracking passwords without permission is illegal and unethical. Only attempt to crack passwords you own or have explicit permission to test.