Password Cracking Overview

Penetration Testing and Password Cracking

• Common tasks include cracking various types of passwords (login, file, etc.)

John the Ripper (JnR)

• A well-known password cracking tool for Windows, Unix, and Mac systems.
• Features:
  • Automatically detects encryption types for common formats.
  • Saves time in finding the right tool to crack specific hashes.
  • Utilizes a dictionary-based approach.
• Common Password List:
  • Rockyou.txt is frequently used.
  • JnR includes its own word lists with thousands of common passwords.

Modes of Operation

1. Single Crack Mode
   • Generates variations of a given string to create potential passwords.
   • Example: Variations like 'Top Gun', 'top gun123', etc.
2. Wordlist Mode
   • Requires a list of passwords from which JnR generates hashes.
   • Effective for common/easily guessable passwords.
3. Incremental Mode
   • Most powerful but time-consuming.
   • Tests all possible character combinations.
   • Use as a last resort for long/complex passwords.

Hash Types and Cracking Examples

• Windows Passwords:
  • Stored in the SAM database using LM/NLM hash format.
  • Command example: john --format=LM wind.txt
• Linux Passwords:
  • Stored in /etc/passwd and /etc/shadow.
  • Use the unshadow command to combine files into one for JnR to process.
  • Example output file: output.DB
• ZIP File Passwords:
  • Use the zip2john utility to extract password hash from ZIP files.
  • Followed by cracking with JnR.

Best Practices for Password Security

• Use strong, long, and complex passwords.
• Avoid password reuse across multiple sites.
• Utilize a password manager to generate/store passwords securely.

Conclusion

• Use John the Ripper responsibly to enhance security and protect against password attacks.
• Support causes like raising funds for children with cancer.