Microsoft Windows Netlogon Remote Protocol (MS-NRPC) is an authentication component of the Active Directory that authenticates users and computer accounts. It uses a known zero-value initialization vector in AES-CFB8 mode.
When encrypting a message consisting of only zeroes with a zero initialization vector, there is a 1 in 256 chance an attacker can successfully authenticate as any domain-joined computer. This allows impersonation of Domain Controllers and makes it possible for an attacker to change the Active Directory password and potentially gain domain administrator privileges.

To abuse this vulnerability an attacker will first need an access to the corporate network.