In a post-exploitation scenario where the attacker has compromised the domain or an account with delegated rights, it’s possible to dump the clear-text passwords of admins without being a Domain Admin*. Furthermore, Microsoft Windows were for many years configured by default to send and accept responses derived from both the LM hash and the NTLM hash, so the use of the NTLM hash provided no additional security while the weaker hash was still present.The two key goals of any attack is access and persistence. On the negative side, the same DES algorithm was used with only 56-bit encryption for the subsequent authentication steps, and there is still no salting. To address the security weaknesses inherent in LM encryption and authentication schemes, Microsoft introduced the NTLMv1 protocol in 1993 with Windows NT 3.1.įor hashing, NTLM uses Unicode support, replacing LMhash= DESeach(DOSCHARSET(UPPERCASE(password)), by NThash= MD4(UTF-16-LE(password)), which does not require any padding or truncating that would simplify the key. These two ciphertext values are concatenated to form a 16-byte value, which is the LM hash. The DES CipherMode should be set to ECB, and PaddingMode should be set to NONE. This generates the 64 bits needed for a DES key.Įach of the two keys is used to DES-encrypt the constant ASCII string resulting in two 8-byte ciphertext values.

These values are used to create two DES keys, one from each 7-byte half, by converting the seven bytes into a bit stream with the most significant bit first, and inserting a null bit after every seven bits (so 1010100 becomes 10101000).

The “fixed-length” password is split into two 7-byte halves.

This password is null- padded to 14 bytes.

The user's password is encoded in the System OEM code page.

The user’s password is converted to UPPERCASE.The user's password is restricted to a maximum of fourteen characters.Support for the legacy LM hash continued in later versions of Microsoft Windows for backward compatibility, but was recommended by Microsoft to be turned off by administrators as of Windows Vista, the protocol is disabled by default, but continues to be used by some non-Microsoft CIFS implementations. LM hash, LanMan hash, or LAN Manager hash is a compromised password hashing function that was the primary hash that Microsoft LAN Manager and Microsoft Windows versions prior to Windows Server NT used to store user passwords.

Lm hash generator