This indicates an attempt against a buffer overflow vulnerability in HP OpenView Network Node Manager.
The vulnerability is caused by the ovwebsnmpsrv.exe process which can be reached remotely through the jovgraph.exe CGI program. It allows remote attackers to execute arbitrary code via unspecified parameters to jovgraph.exe.
HP OpenView Network Node Manager 7.53
HP OpenView Network Node Manager 7.51
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.