AIX(ssha1) Hash

What is AIX(ssha1)?

The **AIX(ssha1)** hash format is a legacy password storage scheme derived from the **Secure Shell (SSH) protocol**, specifically tailored for use in IBM’s AIX operating system. Introduced in the late 1990s as part of SSH-1’s password authentication mechanism, it encodes passwords using a truncated **SHA-1 (Secure Hash Algorithm 1)** hash of the plaintext password, followed by a fixed-length salt (typically 8 bytes) and a 20-byte hash output. The format is structured as `AIX(ssha1)$$`, where the salt is a low-entropy, non-random value (often derived from the username or a static seed), and the hash is the SHA-1 digest of the concatenated password and salt. This scheme was primarily deployed in AIX’s SSH implementations to provide a lightweight alternative to more secure password hashing methods, though it was never designed for modern security standards. Its adoption was driven by compatibility with early SSH versions and the system’s historical reliance on SHA-1 for cryptographic operations, despite SHA-1’s known vulnerabilities.

The **AIX(ssha1)** format is critically vulnerable to cracking due to its reliance on **SHA-1’s inherent weaknesses**, **predictable salts**, and **inefficient resistance to brute-force attacks**. SHA-1’s collision resistance has been broken for decades, and its 160-bit output space is now trivially precomputed using GPU-accelerated rainbow tables or brute-force tools like Hashcat. The fixed or low-entropy salts (often static or username-based) eliminate salt uniqueness, allowing attackers to precompute hashes for common passwords and salts offline. Additionally, the absence of iterative hashing (e.g., no work factor or stretching) enables modern hardware to evaluate millions of guesses per second, rendering the scheme susceptible to **dictionary attacks** and **rainbow table lookups**. Optimizations like **GPU-based SHA-1 cracking** (e.g., via CUDA or OpenCL) further exacerbate the risk, as the lightweight nature of SHA-1 allows for massive parallelization, making recovery of plaintext passwords from stored hashes a matter of hours or days for determined attackers.

Identifying AIX(ssha1) 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 AIX(ssha1), security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack AIX(ssha1)

If you need to recover the plaintext password for a AIX(ssha1) 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.