ophcrack-cli

ophcrack-cli -d <table_directory> -s <target_file> [OPTIONS]

-d <directory>
    Specifies the directory where Ophcrack should look for rainbow tables. This option is crucial for the command to function.

-h
    Displays a help message with available options and exits.

-l
    Lists the rainbow tables found in the specified table directory (via -d).

-n <number>
    Sets the number of CPU cores or threads to utilize for the cracking process, optimizing performance.

-o <file>
    Redirects the cracked passwords and their corresponding hashes to the specified output file.

-p
    Prints the successfully cracked passwords and their hashes to the standard output (console).

-q
    Enables quiet mode, suppressing most informational output during the cracking process.

-s <file>
    Specifies the target file containing hashes to crack. This can be a Windows SAM file, a SYSTEM file, or a plain text file containing hashes (e.g., LM:NTLM format).

-t <tables>
    Specifies which subset of rainbow tables to use for cracking (e.g., "all", "LM", "NTLM", or specific table names).

-v
    Enables verbose output, providing more detailed information about the cracking process.

The ophcrack-cli command is the command-line interface version of Ophcrack, a free and open-source tool designed to crack Windows user passwords. It operates primarily by utilizing pre-computed rainbow tables, which are large datasets that allow for very fast lookup of plaintext passwords from their corresponding hashes. Ophcrack is specifically effective against LM (LAN Manager) and NTLM (NT LAN Manager) hashes, commonly used in older and some current Windows environments.

Users typically provide ophcrack-cli with a directory containing these rainbow tables and a target file, which can be a Windows SAM (Security Account Manager) file, a SYSTEM file, or a plain text file containing extracted hashes. The command then attempts to reverse the hashes into their original passwords using the table data. It is widely used for security auditing, recovering lost Windows passwords, and demonstrating the vulnerabilities of specific hashing algorithms. Its efficiency heavily relies on the availability and completeness of the rainbow tables.

Using ophcrack-cli effectively requires significant storage for rainbow tables (often hundreds of gigabytes). The effectiveness of cracking depends directly on the size and type of available tables and the complexity of the passwords. For modern, complex passwords or newer hashing algorithms, Ophcrack may be less effective than more contemporary tools like hashcat or John the Ripper. Always ensure you have explicit legal authorization to crack passwords, as unauthorized use is illegal and unethical.

Rainbow tables are pre-computed tables used in cryptography to reverse cryptographic hash functions, usually for cracking password hashes. Instead of calculating hash values for every possible password (a brute-force attack), Ophcrack looks up the hash in a rainbow table, which contains pre-calculated chains of hashes and their corresponding plaintext values. This method significantly speeds up the cracking process compared to on-the-fly brute-forcing for known hash types like LM and NTLM.

ophcrack-cli primarily targets LAN Manager (LM) and NT LAN Manager (NTLM) hashes. LM hashes are particularly weak due to their design (case-insensitivity, 7-character limit, broken into two halves), making them very fast to crack. NTLM hashes are more robust than LM but are still vulnerable to rainbow table attacks, especially with large, comprehensive tables. It does not support newer, stronger hashing algorithms or salted hashes often used in modern systems.

To use ophcrack-cli, you must first download or generate appropriate rainbow tables. These tables are typically very large (tens to hundreds of gigabytes) and must match the hash type you intend to crack (e.g., LM or NTLM tables). Without these tables, the command cannot perform its cracking function. The target hashes must also be extracted from the system (e.g., from SAM/SYSTEM files or a registry hive) before they can be fed into ophcrack-cli.

Ophcrack was developed by Objectif Sécurité and first released around 2007, quickly gaining prominence for its innovative use of rainbow tables for Windows password cracking. It was often distributed as a LiveCD/LiveUSB, allowing users to boot directly into an environment capable of cracking passwords from a target system's disk. The ophcrack-cli version provides the core cracking engine without the graphical user interface, making it suitable for scripting and command-line environments. While still functional, its role has somewhat diminished over time with the adoption of stronger password hashing mechanisms and the emergence of more versatile and GPU-accelerated cracking tools.

john(1), hashcat(1), samdump2(1), chntpw(8)