Cisco Type 9 Hash

What is Cisco Type 9?

Cisco Type 9 is a legacy cryptographic hash format introduced in the early 1990s as part of Cisco’s proprietary password storage mechanism, primarily used in IOS (Internetwork Operating System) versions prior to 12.0. Structurally, it combines a truncated MD5 hash (16 bytes) with a 16-byte salt derived from the user’s password, resulting in a 32-byte binary string. The format encodes the salt and hash into an ASCII string of 40 characters, where the first 16 characters represent the salt (hex-encoded) and the next 24 characters represent the truncated MD5 hash (also hex-encoded). This design was intended to mitigate plaintext storage vulnerabilities but lacked modern cryptographic rigor. Cisco Type 9 passwords were commonly found in older router and switch configurations, where security was secondary to functionality, and were later deprecated in favor of stronger mechanisms like SHA-256 or AES encryption.

The vulnerability of Cisco Type 9 stems from its reliance on a weak MD5 truncation (only 128 bits of the 128-bit MD5 output) and the absence of a proper salt iteration mechanism. The fixed-length salt (16 bytes) is often predictable or reused, enabling offline brute-force attacks. Additionally, the lack of salt hashing or key stretching makes it susceptible to rainbow table attacks, as the same salt is applied uniformly. Modern GPU-accelerated cracking tools, such as Hashcat or John the Ripper, can efficiently brute-force truncated MD5 hashes due to their parallelizable nature, often cracking Type 9 passwords in minutes. The absence of collision resistance (MD5 is now considered broken for security purposes) further exacerbates risks, as identical inputs may produce valid-looking hashes, complicating integrity verification.

Identifying Cisco Type 9 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 Cisco Type 9, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack Cisco Type 9

If you need to recover the plaintext password for a Cisco Type 9 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.