md4(utf16($pass)) Hash

What is md4(utf16($pass))?

MD4 (Message-Digest algorithm 4) was designed by Ronald L. Rivest in 1990 as a 128-bit hash function intended for digital signature applications, though it was later repurposed for password storage. The algorithm processes input data in 512-bit blocks using a fixed structure of three compression rounds (each consisting of 16 operations) that mix bitwise operations (AND, OR, XOR) with modular arithmetic and a predefined constant schedule. When applied as `md4(utf16($pass))`, the input string is first encoded into UTF-16 (Little-Endian by default), which doubles the byte length of non-ASCII characters and introduces implicit padding (e.g., `\0` bytes for odd-length strings), before being hashed. This format was historically used in early authentication systems like early versions of Kerberos or proprietary protocols, though its cryptographic weaknesses rendered it unsuitable for modern security requirements.

The vulnerability of `md4(utf16($pass))` stems from fundamental flaws exacerbated by implementation choices. MD4’s design lacks avalanche effects—minor input changes rarely alter the output significantly—enabling brute-force attacks via rainbow tables or precomputed hashes, especially when combined with UTF-16’s predictable padding (e.g., `\0` bytes). The absence of salting (or weak salts) in many deployments collapses into a single hash space, allowing attackers to reuse precomputed tables across systems. Additionally, MD4’s parallelizable structure is highly optimized for GPU/FPGA acceleration (e.g., via CUDA or OpenCL), enabling massive parallel cracking (e.g., 100M+ hashes/sec on modern hardware). Collision resistance is nonexistent—MD4 suffers from practical collision attacks (e.g., forged certificates via ROCA-like exploits) and was broken in 2005, rendering it catastrophically insecure for password storage. The UTF-16 encoding further complicates analysis by introducing non-deterministic byte-order dependencies and length extensions, though these do not mitigate the core cryptographic failures.

Identifying md4(utf16($pass)) 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 md4(utf16($pass)), security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack md4(utf16($pass))

If you need to recover the plaintext password for a md4(utf16($pass)) 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.