Vulnerability Note VU#602801

Consona (formerly SupportSoft) Intelligent Assistance Suite (IAS) cross-site scripting, ActiveX, and Repair Service vulnerabilities

Overview

Consona (formerly SupportSoft) Intelligent Assistance Suite (IAS) contains a set of vulnerabilities that collectively could allow an attacker to execute arbitrary code on a remote system.

I. Description

In 2009, Consona acquired SupportSoft's enterprise software assets, including web-based assistance software called Intelligent Assistance Suite (IAS). IAS client components are delivered via ActiveX controls, Netscape-style plugins, or standalone installers. IAS runs on Microsoft Windows platforms. Consona products affected by these vulnerabilities include Consona Live Assistance, Consona Dynamic Agent, Consona Subscriber Assistance, Repair Manager, Consona Subscriber Activiation, and Subscriber Agent.

IAS contains vulnerabilities in different components.

1. Cross-site scripting (XSS) in ns6plugindestructor.asp
2. Unsafe methods provided by SdcUser.TgConCtl ActiveX control (tgctlcm.dll)
3. Buffer overflow in SdcUser.TgConCtl ActiveX control (tgctlcm.dll)
4. Local privilege elevation in Repair Service (tgsrv.exe) (only installed on Windows Vista and Windows 7)

Using several of these vulnerabilities, an attacker can execute arbitrary code on a vulnerable system. For example, the XSS vulnerability can be used to instantiate the SdcUser.TgConCtl control, which then can be used to download and execute arbitrary programs using the unsafe methods provided by the control. The Repair Service can be used to elevate from user (or Low-Rights IE) privileges to SYSTEM.

Further details are available in Rubén Santamarta's slides from Rooted CON 2010.

II. Impact

By convincing a user to view a specially crafted HTML document (web page, HTML email message), an attacker could execute arbitrary code with the privileges of the user, and possibly gain SYSTEM privileges via the Repair Service.

III. Solution

Apply patches

Sites providing IAS/Consona support services should apply the appropriate patches referenced in the April 2010 Security Bulletin.

Remove n6plugindestructor.asp

To remove the initial cross-site scripting vector, sites providing IAS/Consona support services can remove ns6plugindestructor.asp from the support web site. Removing this file is unlikely to reduce functionality, but may have side effects.

Limit domain access to the SdcUser.TgConCtl ActiveX control

SupportSoft ActiveX controls can only be scripted from sites that contain valid license information. Following the guidance in the April 2010 Security Bulletin, sites providing IAS/Consona support services can augment domain access restrictions by listing allowed domains in the Windows registry and hosting controls using HTTPS to reduce the possibility of DNS spoofing attacks.

Disable the SdcUser.TgConCtl ActiveX control in Internet Explorer

Web clients of IAS/Consona support services can disable the vulnerable ActiveX control in Internet Explorer by setting the kill bit for the following CLSID:

{01113300-3E00-11D2-8470-0060089874ED}

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 into the Windows registry:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINESOFTWAREMicrosoftInternet ExplorerActiveX Compatibility{01113300-3E00-11D2-8470-0060089874ED}]
"Compatibility Flags"=dword:00000400

Disabling this control will likely reduce functionality.

Vendor Information

Vendor	Status	Date Notified	Date Updated
Consona	Affected	2010-03-26	2010-05-18

References

http://wintercore.com/en/component/content/article/7-media/18-wintercore-releases-an-advisory-for-consona-products.html
http://www.wintercore.com/downloads/rootedcon_0day.pdf
http://www.rootedcon.es/eng/rooted-con-2010/schedule.html
http://www.consona.com/Content/CRM/Support/SecurityBulletin_April2010.pdf
http://www.consona.com/news/consonaacquiressupportsoft.aspx
http://www.consona.com/news/SupportSoftClose.aspx
http://www.supportsoft.com/Downloads/PDF/brochures/IAS_for_DSP_2008.pdf
http://support.microsoft.com/kb/240797

Credit

This information is based on research by Rubén Santamarta. Thanks to Rubén and Consona for following responsible vulnerability disclosure practices.

This document was written by Art Manion.

Other Information

Date Public:	2010-03-19
Date First Published:	2010-05-06
Date Last Updated:	2010-05-18
CERT Advisory:
CVE-ID(s):
NVD-ID(s):
US-CERT Technical Alerts:
Metric:	15.52
Document Revision:	27