This policy setting determines whether the LAN Manager (LM) hash value for the new password is stored when the password is changed. The LM hash is relatively weak and prone to attack compared to the cryptographically stronger Microsoft Windows NT * hash. Note Older operating systems and some third-party applications may fail when this policy setting is enabled. Also you will need to change the password on all accounts after you enable this setting. Vulnerability: The SAM file can be targeted by attackers who seek access to username and password hashes. Such attacks use special tools to crack passwords, which can then be used to impersonate users and gain access to resources on your network. These types of attacks will not be prevented if you enable this policy setting, but it will be much more difficult for these types of attacks to succeed. Counter Measure: Configure the Network security: Do not store LAN Manager hash value on next password change setting to Enabled. Require all users to set new passwords the next time they log in to the domain so that LAN Manager hashes are removed. Potential Impact: Earlier operating systems such as Windows 95, Windows 98, and Windows ME as well as some third-party applications will fail. Fix: (1) GPO: Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\Network security: Do not store LAN Manager hash value on next password change (2) REG: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa!NoLMHash