Software Engineering Institute

The VeriSign Configuration Checker ActiveX control is provided by web-based digital certificate enrollment sites and also by the VeriSign Managed PKI OnSiteMSI package. This control is vulnerable to a stack buffer overflow in the VerCompare() method, which can allow an overwrite of the process Structured Exception Handler (SEH).

By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code with the privileges of the user. The attacker could also cause Internet Explorer (or the program using the WebBrowser control) to crash.

Apply an update

VeriSign Japan has published a page to check if the vulnerable ActiveX control is installed. If the vulnerable control is found, a download link to an update is provided. This update removes the VSCnfChk.dll file, which provides the vulnerable ActiveX control. Please note that this update will not prevent the vulnerable control from being installed again in the future. Therefore, we recommend the following workarounds:

Disable the VeriSign Configuration Checker ActiveX control in Internet Explorer

The vulnerable ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

{08F04139-8DFC-11D2-80E9-006008B066EE}
More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{08F04139-8DFC-11D2-80E9-006008B066EE}]
"Compatibility Flags"=dword:00000400
Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an attacker) appears to prevent exploitation of this and other ActiveX vulnerabilities. Instructions for disabling ActiveX in the Internet Zone can be found in the "Securing Your Web Browser" document.