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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2004.0211 -- iDEFENSE Security Advisory 03.09.04 *UPDATE* Microsoft Outlook "mailto:" Parameter Passing Vulnerability 16 March 2004 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Microsoft Outlook 2002 Microsoft Office XP Publisher: iDEFENSE Operating System: Windows Server 2003 Windows XP Windows 2000 Windows NT Windows ME Windows 98 Impact: Execute Arbitrary Code/Commands Access Required: Remote CVE Names: CAN-2004-0121 Ref: ESB-2004.0191 - --------------------------BEGIN INCLUDED TEXT-------------------- On March 10, 2004, Microsoft upgraded the severity of iDEFENSE Security Advisory 03.09.04 from "Important" to "Critical". This was done as alternate attack vectors were uncovered that bypassed the originally proposed workarounds. iDEFENSE is re-releasing the advisory to reflect this newly discovered information. Details regarding the following information have been added to the Analysis section of the advisory: - - It is possible for an attacker to force Outlook 2002 to start in the "Outlook Today" view. As a result, the originally proposed workaround of setting the default view to something other than "Outlook Today" is not effective. Pedram Amini Assistant Director, iDEFENSE Labs - ------------------------------------------------------------------------ Microsoft Outlook "mailto:" Parameter Passing Vulnerability iDEFENSE Security Advisory 03.09.04 www.idefense.com/application/poi/display?id=79&type=vulnerabilities March 09, 2004 I. BACKGROUND Microsoft Outlook provides an integrated solution for managing and organizing e-mail messages, schedules, tasks, notes, contacts, and other information. More information is available at http://www.microsoft.com/outlook/. II. DESCRIPTION Insufficient filtering of parameters passed to Microsoft Corp.'s Outlook e-mail client via the "mailto:" URI (RFC 2368) allows for remote script execution within the "Local Machine" zone. When Outlook is installed, it is enabled as the default e-mail handler. A "mailto:" URI will spawn Outlook with the following command line switches: OUTLOOK.EXE -c IPM.Note /m "... The problem manifests when the string '"' is interspersed within the URI, thereby allowing an attacker to manipulate the command line switches that Outlook is instantiated with. The following example URI: ... mailto:aa" /profile "xx" ... causes Internet Explorer to start Outlook as such: OUTLOOK.EXE -c IPM.Note /m "aa" /profile "xx" The provided URI can be of the form 'javascript:...', allowing an attacker to execute arbitrary script code. In some implementations, this script code executes under the context of the "Local Machine Zone". An attacker does not need to socially engineer a target user into clicking on a malicious link, as the process can be started automatically by embedding the "mailto:" URI within an HTML IMG tag. III. ANALYSIS Successful exploitation allows an attacker to remotely execute arbitrary code under the context of the "Local Machine" zone. Script code executing with such privileges can be crafted to retrieve and execute arbitrary third-party code, thereby leading to further compromise. Microsoft had originally stated that only users who had set "Outlook Today" as their default Outlook folder home page were affected. Further analysis has revealed that users are not protected by changing their default view. Additional manipulation allows an attacker to force Outlook to start within the "Outlook Today" view with a specified URI. This can be accomplished by first starting Outlook while specifying "Outlook Today" as the starting view and then passing in a URI via the '/recycle' command line switch. Another potential exploit vector may involve the usage of the command line switch '/select outlook:outlook%20today'. iDEFENSE has proof of concept exploit code demonstrating the impact of this vulnerability. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in Microsoft Outlook 2002. V. WORKAROUND iDEFENSE is currently unaware of any valid workarounds. VI. VENDOR RESPONSE/FIX Microsoft has released the following patches to address this issue: Microsoft Office XP Service Pack 3 http://www.microsoft.com/downloads/details.aspx?FamilyId=85AF7BFD-6F69-4 289-8BD1-EB966BCDFB5E&displaylang=en VII. CVE INFORMATION The Mitre Corp.'s Common Vulnerabilities and Exposures (CVE) Project has assigned CAN-2004-0121 to this issue. VIII. DISCLOSURE TIMELINE October 10, 2003 Vulnerability acquired by iDEFENSE November 12, 2003 Initial vendor notification November 12, 2003 Initial vendor response November 21, 2003 iDEFENSE clients notified March 09, 2004 Coordinated public disclosure March 11, 2004 Updated advisory IX. CREDIT Jouko Pynnönen (http://iki.fi/jouko) is credited with this discovery. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. This security bulletin is provided as a service to AusCERT's members. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBQFZleih9+71yA2DNAQJyPQP/cwKnS5NjQwmjh764NHwt7vaag2DQh30V sU2CCGJqgndrZbbBVucupy+SJko5wBy/0HaS/wB2crECuIN9KPdznnqywv7y/t46 mUuFem+QQfw0CGlJZWyvdG+UQV5X3A4ZX0528QNWNu+a5RdrSbh+okMZVMe6e6ci 9tMsRgsqqLs= =0Bpv -----END PGP SIGNATURE-----