This indicates an attack attempt against a denial-of-service vulnerability in Microsoft Netlogon RPC Service.
The vulnerability is caused by an error when the vulnerable software handles a malicious RPC request. It allows a remote attacker to restart affected versions of the Windows Server via sending a crafted web page.
Windows Server 2003 Service Pack 2
Windows Server 2003 x64 Edition Service Pack 2
Windows Server 2003 with SP2 for Itanium-based Systems
Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2*
Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2*
Windows Server 2008 R2 for x64-based Systems
Denial of service
Apply the patch, available at the vendor's website: