This indicates an attack attempt against a Remote Code Execution vulnerability in Unitronics VisiLogic OPLC TeeCommander.
The vulnerability, which is located in an ActiveX control, can be exploited through a vulnerable method. An attacker can exploit this by tricking an unsuspecting user into visiting a malicious webpage and execute arbitrary code within the context of the users' browser.
Unitronics VisiLogic OPLC IDE before 9.8.02
System Compromise: Remote attackers can execute arbitrary code within the context of the target user's browser
Currently we are unaware of any vendor supplied patch for this issue