Software Engineering Institute

Microgaming provides software for online gaming, including online casinos. The Microgaming Download Helper ActiveX control, provided by dlhelper.dll, is vulnerable to stack buffer overflow. Older versions of the control are referred to as "WebHandler Class."

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 the web browser to crash.

Apply an update

This issue is addressed in version 7.2.0.19 of the Download Helper ActiveX control. Users of the Download Helper ActiveX control can perform the update by following these steps:

1. Go to %windir%\Downloaded Program Files\
2. Right-click on Download Helper Class
3. Click Update
4. Verify that the control is updated to version 7.2.0.19 or later

Disable the Download Helper ActiveX control in Internet Explorer

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

{AED98630-0251-4E83-917D-43A23D66D507}
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\{AED98630-0251-4E83-917D-43A23D66D507}]
"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.