RAdmin v2.x Hash

What is RAdmin v2.x?

RAdmin v2.x employs a proprietary cryptographic hash format designed in the late 1990s as part of its remote administration suite for Windows systems, primarily to secure client-server authentication and session integrity. The format combines a modified MD4-based hash with a custom challenge-response mechanism, where the client generates a hash of a dynamic nonce (challenge) concatenated with a static password hash stored on the server. The structure lacks standardized cryptographic rigor, instead relying on a 128-bit (16-byte) output derived from an iterative hashing process—typically 3–5 rounds of MD4 with partial key mixing—to produce a "session key" used for symmetric encryption. While intended for lightweight authentication, its design prioritized compatibility over security, making it susceptible to offline attacks due to the absence of salting or key stretching, and its reliance on predictable iteration counts.

The vulnerability of RAdmin v2.x stems from its reliance on MD4’s inherent weaknesses, including fast collision resistance (now broken) and poor avalanche effects, compounded by the absence of per-user salting or adaptive work factors. Offline attackers can leverage GPU-accelerated brute-force tools (e.g., Hashcat) to crack hashes at rates exceeding 100,000 attempts per second, as the fixed iteration count and lack of computational overhead allow for optimized rainbow table precomputation. Additionally, the format’s reliance on a static password hash (derived from a simple MD4 iteration) enables dictionary attacks against weak credentials, while the challenge-response design—though dynamic—does not mitigate against replay attacks if session keys are reused or intercepted. Post-quantum vulnerabilities further exacerbate risks, as MD4’s structure is susceptible to Grover-based optimization.

Identifying RAdmin v2.x 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 RAdmin v2.x, security researchers analyze the hash against a strict regular expression (regex) signature (shown above) to find structural matches.

How to Crack RAdmin v2.x

If you need to recover the plaintext password for a RAdmin v2.x 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.