This indicates an attack attempt to exploit a Cross-Site Scripting vulnerability in Trend Micro InterScan Messaging Security.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling maliciously crafted HTTP requests. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
Trend Micro InterScan Messaging Security Suite 18.104.22.1681 and earlier versions
System Compromise: Remote attackers can execute arbitrary script code in the context of the affected server.
Currently we are unaware of any vendor supplied patch or updates available for this issue.