This indicates an attack attempt against a Buffer Overflow vulnerability in Symantec Endpoint Protection Manager.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
Symantec Endpoint Protection Manager Console 12.1.0 to 12.1.2
Symantec Endpoint Protection Center Small Business Edition Console 12.1.0 to 12.1.2
System Compromise: Remote attackers can gain control of vulnerable systems
Apply the latest patch or upgrade from the vendor.