This indicates an attack attempt to exploit a stack-based Buffer Overflow vulnerability in Siemens SIMATIC WinCC.
The vulnerability, which is located in "WebClientInstall.dll" ActiveX control, can be exploited through misuse of a vulnerable method. It may allow remote attackers to execute arbitrary code in the context of the application, using the affected ActiveX control. Failed exploit attempts will likely cause the program to crash, resulting in a denial of service condition.
Siemens SIMATIC WinCC prior to 7.2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply a patched version of the product from the vendor, which is available to paid customers.