OSX v10.4 Hash

What is OSX v10.4?

The OS X v10.4 hash format, also known as the "macOS 10.4" or "Tiger" password hash, was introduced by Apple in 2005 as part of its transition from the older Unix-style DES-based cryptographic schemes to a more secure, though still legacy, password hashing mechanism. Structurally, this format combines a salted MD5 hash with a subsequent SHA-1-based iteration process, resulting in a 128-bit (16-byte) salt followed by a 160-bit (20-byte) SHA-1 digest of the salted password concatenated with a fixed string ("\x0B\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"). The stored hash is a binary blob of 36 bytes (128-bit salt + 20-byte SHA-1 output), prefixed with a 4-byte magic identifier (`"$2a$"` in a Unix-style format, though Apple’s implementation deviates from OpenBSD’s original intent). This scheme was designed to mitigate the weaknesses of plain MD5 by introducing a salt and iterative hashing, though it retained the fundamental flaw of using weak cryptographic primitives for password storage. Its primary use-case was securing local user authentication in macOS 10.4, though it was quickly superseded by more robust algorithms like bcrypt or PBKDF2 in later iterations.

The OS X v10.4 hash format is highly vulnerable to cracking due to its reliance on MD5 and SHA-1, both of which are now considered cryptographically broken and susceptible to collision attacks and preimage attacks. The absence of a meaningful iteration count (unlike bcrypt or PBKDF2) allows modern hardware to brute-force the hash at an alarmingly fast rate, with GPUs and FPGA-based attackers achieving millions of hashes per second. Additionally, the fixed-length salt (16 bytes) and the use of SHA-1 (which has known collision vulnerabilities) enable rainbow table attacks and brute-force dictionary cracking. Tools like Hashcat and John the Ripper can exploit these weaknesses, particularly when combined with GPU acceleration, rendering the format effectively insecure for modern security standards. The lack of a salted iterative key derivation function (like bcrypt’s work factor) means the hashing process is computationally trivial compared to contemporary standards, making password recovery feasible even for weak passwords.

Identifying OSX v10.4 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 OSX v10.4, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack OSX v10.4

If you need to recover the plaintext password for a OSX v10.4 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.