Software Engineering Institute

The InstallShield Update Service, now known as Macrovision FLEXnet Connect, contains an ActiveX control called Update Service Agent. This ActiveX control is a component that is included with some Macrovision and InstallShield Windows software installers and is provided by the file isusweb.dll. The Update Service Agent ActiveX control contains buffer overflow vulnerabilities in the Download() and DownloadAndExecute() methods.

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

This issue is addressed in the FLEXnet Connect 6.0 Security Patch, which is available in the Acresso support document Q113020. This update addresses the buffer overflows and removes the "Safe for Scripting" setting of the vulnerable control, which prevents the control from being scripted by Internet Explorer. Because the vulnerable control may be provided to end-users who do not have the FLEXnet Connect SDK installed, please consider the following workarounds:

Disable the Update Service Agent ActiveX control in Internet Explorer

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

{E9880553-B8A7-4960-A668-95C68BED571E}
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\{E9880553-B8A7-4960-A668-95C68BED571E}]
"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.