This indicates an attack attempt against a buffer-overflow vulnerability in Trend Micro OfficeScan.
The vulnerability is caused by an error when the vulnerable software handles a specially crafted HTTP request. It allows a remote attacker to execute arbitrary code.
Trend Micro OfficeScan 8.0 Service Pack 1
Trend Micro OfficeScan 8.0
Trend Micro OfficeScan 7.3
Denial of Service
Apply the appropriate patch from the vendor:
Trend Micro OfficeScan 8.0 Service Pack 1:
Trend Micro OfficeScan 7.3: