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CERT® Advisory CA-2002-13 Buffer Overflow in Microsoft's MSN Chat ActiveX ControlOriginal release date: May 10, 2002Last revised: August 28, 2002 Source: CERT/CC A complete revision history can be found at the end of this file. Systems AffectedMicrosoft Windows systems with one or more of the following:
OverviewMicrosoft's MSN Chat is an ActiveX control for Microsoft Messenger, an instant messaging client. A buffer overflow exists in the ActiveX control that may permit a remote attacker to execute arbitrary code on the system with the privileges of the current user. I. DescriptionA buffer overflow exists in the "ResDLL" parameter of the MSN Chat ActiveX control that may permit a remote attacker to execute arbitrary code on the system with the privileges of the current user. This vulnerability affects MSN Messenger and Exchange Instant Messenger users. Since the control is signed by Microsoft, users of Microsoft's Internet Explorer (IE) who accept and install Microsoft-signed ActiveX controls are also affected. The Microsoft MSN Chat control is also available for direct download from the web. The <object> tag could be used to embed the ActiveX control in a web page. If an attacker can trick the user into visiting a malicious site or the attacker sends the victim a web page as an HTML-formatted email message or newsgroup posting then this vulnerability could be exploited. This acceptance and installation of the control can occur automatically within IE for users who trust Microsoft-signed ActiveX controls. When the web page is rendered, either by opening the page or viewing the page through a preview pane, the ActiveX control could be invoked. Likewise, if the ActiveX control is embedded in a Microsoft Office (Word, Excel, etc.) document, it may be executed when the document is opened. According to the Microsoft Advisory (MS02-022): It's important to note that this control is used for chat rooms on several MSN sites in addition to the main MSN Chat site. If you have successfully used chat on any MSN-site, you have downloaded and installed the chat control. The CERT/CC has published information on ActiveX in Results of the Security in ActiveX Workshop (pdf) and CA-2000-07. This issue is also being referenced as CAN-2002-0155: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-0155 II. ImpactA remote attacker may be able to execute arbitrary code with the privileges of the current user. III. SolutionApply a patch from your vendor On June 11, 2002, Microsoft updated Microsoft Advisory (MS02-022) and released a new patch that remedies the vulnerability for users that downloaded and accepted the control. The previous solution did not fully protect against this action and it was possible for an attacker to load the vulnerable control, even though the previous patch and updated versions had been installed. The new patch is available at http://www.microsoft.com/Downloads/Release.asp?ReleaseID=39632. All users should apply this patch, even if you previously installed an updated version of your software. This patch supercedes the patch information below.
If you have updated your software prior to June 11, 2002, you should reinstall the software from the following locations:
Microsoft also suggests that the following Microsoft mail products: Outlook 98 and Outlook 2000 with the Outlook Email Security Update, Outlook 2002, and Outlook Express will block the exploitation of this vulnerability via email because these products will open HTML email in the Restricted Sites zone. Other mitigation strategies include opening web pages and email messages in the Restricted Sites zone and using email clients that permit users to view messages in plain-text. Likewise, it is important for users to realize that a signed control only authenticates the origin of the control and does not imply any information with regard to the security of the control. Therefore, downloading and installing signed controls through an automated process is not a secure choice. Appendix A. - Vendor InformationThis appendix contains information provided by vendors for this advisory. As vendors report new information to the CERT/CC, we will update this section and note the changes in our revision history. If a particular vendor is not listed below, please check the Vulnerability Note (VU#713779) or contact your vendor directly. MicrosoftSee http://www.microsoft.com/technet/treeview/default.asp ?url=/technet/security/bulletin/MS02-022.asp The CERT/CC acknowledges the eEye Team for discovering and reporting on this vulnerability and thanks Microsoft for their technical assistance. Feedback can be directed to the author: Jason A. Rafail This document is available from: http://www.cert.org/advisories/CA-2002-13.html CERT/CC Contact Information
Phone: +1 412-268-7090 (24-hour hotline) Fax: +1 412-268-6989 Postal address: CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends. Using encryptionWe strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from If you prefer to use DES, please call the CERT hotline for more information. Getting security informationCERT publications and other security information are available from our web site
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Copyright 2002 Carnegie Mellon University. Revision History May 10, 2002: Initial release August 28, 2002: Updated patch information |
