This indicates an attack attempt to exploit a Privilege Escalation vulnerability in Microsoft Windows.
The vulnerability is caused by an error in win32k.sys when handling a crafted application. An attacker can exploit this to elevate their privileges on vulnerable systems.
Windows Server 2008
Windows Server 2012 and Windows Server 2012 R2
Windows RT 8.1
Privilege Escalation: Remote attackers can leverage their privilege on the vulnerable systems.
Apply the most recent upgrade or patch from the vendor