ophcrack

ophcrack-cli [OPTIONS]
The primary command-line interface for Ophcrack. While a GUI version is common, ophcrack-cli provides programmatic control for hash cracking.

-t, --tables directory
    Specifies the directory where the rainbow tables are located. These tables are essential for cracking.

-d, --database file
    Specifies the input file containing LM or NTLM hashes to be cracked, often a Windows SAM file or a hash dump.

-l, --log file
    Logs the program's output and progress to the specified file instead of the console.

-p, --passwords file
    Outputs successfully cracked passwords to the specified file.

-c, --config file
    Uses an alternative configuration file for Ophcrack settings.

-h, --help
    Displays a help message with command-line options and usage information.

-v, --version
    Displays the version information of the Ophcrack CLI tool.

Ophcrack is a free, open-source tool designed to crack Windows LM and NTLM password hashes using rainbow tables. Unlike brute-force or dictionary attacks that try every possible password, Ophcrack leverages precomputed tables of hash values. This allows for extremely fast recovery of passwords, often within minutes, if the password's hash is present in the loaded rainbow tables.

It's particularly effective against older Windows operating systems (like XP, 2000, Vista, 7) that primarily use LM and NTLM hashes. The tool can extract hashes directly from a Windows SAM file or process hashes dumped by other utilities. While highly efficient for its target hash types, its effectiveness is limited by the size and scope of the rainbow tables and struggles with modern, salted hashes or very long, complex passwords that are not precomputed.

Ophcrack's primary method relies on rainbow tables, which are large precomputed datasets.
Limitations include:
It requires substantial disk space for rainbow tables.
It is less effective against modern, salted password hashes (e.g., NTLMv2, bcrypt, scrypt, Argon2) as rainbow tables are designed for unsalted or weakly salted hashes.
It cannot crack passwords whose hashes are not present within the loaded rainbow tables.
Ethical considerations: Ophcrack should only be used on systems for which you have explicit permission to access or audit. Unauthorized use is illegal and unethical.

While this documentation focuses on the ophcrack-cli command-line interface, Ophcrack is also widely known for its intuitive graphical user interface (GUI). The GUI version simplifies the process, making it accessible to users who prefer a visual interaction for loading tables, hashes, and viewing results.

Rainbow tables are precomputed tables used in cryptography for reversing cryptographic hash functions, usually for cracking password hashes. They are an optimization over a simple hash chain that allows for a trade-off between time and memory, significantly speeding up the cracking process by reducing the need for brute-force computations at runtime.

Ophcrack was initially released around 2004-2006 by the Ophcrack project team. It quickly gained prominence as a highly effective and user-friendly tool for cracking Windows LM and NTLM hashes, particularly for older Windows versions (XP, 2000, Vista, 7). Its innovation lay in popularizing and implementing the concept of rainbow tables for password recovery. While the underlying hash types it targets (LM/NTLM) are becoming less prevalent for new systems due to stronger modern hashing algorithms and password policies, Ophcrack remains a valuable tool for auditing legacy systems or in specific forensic scenarios.

john(1), hashcat(1), passwd(1), chntpw(8)