This indicates an attack attempt against a code-execution vulnerability in Microsoft SMB Client.
The vulnerability is caused by an error when the vulnerable software handles a malicious SMB response. It allows a remote attacker to execute arbitrary code via sending a crafted SMB response.
Windows 7 for 32-bit Systems
Windows 7 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems*
Windows Server 2008 R2 for Itanium-based Systems
System Compromise: Remote attackers can gain control of vulnerable systems.
Refer to the vendor's web site for the suggested workaround: