OSX v10.6 Hash

What is OSX v10.6?

The OS X v10.6 password hash format, also known as **macOS 10.6 (Snow Leopard) password hashes**, was introduced as part of Apple’s transition from the legacy Unix password scheme to a more secure, native implementation of Unix-style authentication. Structurally, this format stores passwords in a **SHA-1-based** scheme with a **salted** (though poorly implemented) and **iterated** hashing mechanism, designed to resist brute-force attacks relative to its time. The hash is typically stored in the `/etc/master.passwd` file (or its shadow counterpart) and follows a specific binary layout: a 16-byte salt (derived from the user’s UID and a fixed seed), followed by a SHA-1 hash of the salted password repeated **10,000 times** (a weak iteration count by modern standards). This scheme was intended to improve upon earlier Apple password formats (e.g., the unsalted MD5 hashes of older systems) by incorporating salting and hashing iterations, though its security assumptions were quickly outdated. The primary use-case was local user authentication within macOS 10.6, leveraging the BSD-derived authentication framework with Pluggable Authentication Modules (PAM).

The OS X v10.6 hash format is vulnerable to cracking primarily due to its **insufficient iteration count**, **predictable salt structure**, and **inefficient resistance to GPU/ASIC optimization**. The 10,000 SHA-1 iterations were designed to slow down brute-force attacks on single-core CPUs of the era, but modern hardware (GPUs, FPGAs, and ASICs) can evaluate billions of hashes per second, rendering this iteration count trivial to bypass. Additionally, the salt is derived from the user’s UID and a fixed seed (e.g., `uid % 0x10000`), making it **partially predictable** and reducing the entropy of the salt space. Tools like **Hashcat** and **John the Ripper** can exploit these weaknesses using optimized GPU kernels (e.g., SHA-1 in OpenCL) and rainbow table precomputations, further accelerating recovery. The lack of a **cryptographic salt** (e.g., a true random 128-bit salt) and the **collision susceptibility of SHA-1** (now considered broken for security purposes) compound the format’s vulnerability, allowing attackers to crack hashes efficiently even with weak passwords.

Identifying OSX v10.6 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 v10.6, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack OSX v10.6

If you need to recover the plaintext password for a OSX v10.6 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.