This module triggers a null pointer dereference vulnerability in the SMB service by sending a malformed FileNormalizedNameInformation SMBv3 request over a named pipe. For most systems, this attack requires authentication, except in the special case of Windows Domain Controllers, where unauthenticated users can always open named pipes as long as they can establish an SMB session.
The vulnerability has been dubbed PrintNightmare and is tracked as CVE-2021-34527. The flaw is due to the Windows Print Spooler service improperly performing privileged file operations. Microsoft says the flaw can be exploited by an authenticated user calling RpcAddPrinterDriverEx(). When exploited, an attacker gains SYSTEM privileges and can execute arbitrary code, install programs, view, change, or delete data or create new accounts with full user rights.