Software Engineering Institute

Microsoft Speech API is a software package that provides text-to-speech and speech recognition capabilities. The Microsoft Speech API includes ActiveX controls called ActiveListen and ActiveVoice, which are provided by Xlisten.dll and XVoice.dll, respectively. These ActiveX controls contain multiple buffer overflow vulnerabilities.

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 by Microsoft Security Bulletin MS07-033. This update sets the kill bit for the vulnerable controls. Please also consider the following workarounds

Disable the Speech API ActiveX controls in Internet Explorer

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

{4E3D9D1F-0C63-11D1-8BFB-0060081841DE}
{EEE78591-FE22-11D0-8BEF-0060081841DE}
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 these controls:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{4E3D9D1F-0C63-11D1-8BFB-0060081841DE}]
"Compatibility Flags"=dword:00000400

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{EEE78591-FE22-11D0-8BEF-0060081841DE}]
"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.