Software Engineering Institute

SonicWall NetExtender is an SSL VPN client that is implemented by using an ActiveX control. The NELaunchCtrl ActiveX control, which is provided by NELaunchX.dll, contains a stack buffer overflow in the AddRouteEntry() method.

Exploit code for this vulnerability is publicly available.

By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), a remote, unauthenticated attacker may be able to execute arbitrary code with the privileges of the user on a vulnerable system.

Apply an update
This vulnerability is addressed in the client software provided by the 2.5 firmware for the SonicWall NetExtender 4000 and 2000 series VPN units. This update provides version 2.5.0.53 of the NELaunchCtrl ActiveX control. The vulnerability is also addressed by the 2.1 Patch Build for the SonicWall NetExtender 200 series VPN units. This update provides version 2.1.0.51 of the NELaunchCtrl ActiveX control. These updates can be obtained from the SonicWall Support page. Please note that the client systems must connect to a NetExtender SSL VPN unit to obtain the fixed control. If you are unable to obtain a fixed version of the control, please consider the following workarounds:

Disable the NELaunchCtrl ActiveX control in Internet Explorer

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

{6EEFD7B1-B26C-440D-B55A-1EC677189F30}
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\{6EEFD7B1-B26C-440D-B55A-1EC677189F30}]
"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.