Sybase ASE Hash

What is Sybase ASE?

The Sybase Adaptive Server Enterprise (ASE) cryptographic hash format, primarily employed in older versions of Sybase SQL Server (pre-15.x) and derived systems like Microsoft SQL Server 2000, is a proprietary password storage mechanism designed for backward compatibility with legacy authentication schemes. Structurally, it combines a truncated MD4 hash (160-bit output reduced to 128 bits) with a fixed-length salt derived from the username, concatenated as a 32-byte (256-bit) binary string. The format stores the username (null-padded to 16 bytes), a 4-byte length prefix, and the truncated MD4 hash of the concatenated username and password, resulting in a 32-byte hash block. This scheme was intended for lightweight authentication in enterprise database environments where performance outweighed security concerns, particularly in environments where password complexity was low and brute-force resistance was secondary to system stability.

The Sybase ASE hash format is vulnerable to cracking due to its reliance on MD4’s inherent weaknesses, lack of salting robustness, and susceptibility to GPU-accelerated attacks. MD4’s 128-bit truncation eliminates collision resistance, enabling rainbow table precomputation for common passwords, while the salt—derived predictably from the username—fails to mitigate brute-force attempts effectively. Modern GPU clusters (e.g., using CUDA-optimized tools like Hashcat) can crack these hashes at rates exceeding 100,000 attempts per second, exacerbated by the absence of iterative hashing or key stretching. Additionally, the fixed-length structure and lack of peppering or adaptive work factors render it incompatible with modern cryptographic best practices, making it trivially vulnerable to offline dictionary attacks.

Identifying Sybase ASE Hashes

Identifying a hash blindly is often difficult because multiple algorithms can output strings of the exact same length. For example, a standard 32-character hexadecimal string could be MD5, NTLM, MD4, or LM. To definitively identify Sybase ASE, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Sybase ASE

If you need to recover the plaintext password for a Sybase ASE hash during a penetration test or forensics investigation, you must supply the correct module ID to your cracking software. Use the exact commands provided at the top of this page to target the hash successfully.