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Messages exploiting the "WMF" flaw (CVE-2005-4560)

Public Advisories/Alerts Articles by Cert-IST Useful links In the Press - Events Printable version		Accueil | Resources | Public Advisories/Alerts | Alerts Reference: CERT-IST/AL-2006.001 Version: 1.0 Version date: 02 January 2006 Vulnerability Classification Risk: high Impact: Get access Confidence: Vendor-acknowledged Attack expertise: Beginner Attack requirements: Remote (no account) over a standard service System Information Affected Platform(s): Microsoft Windows systems Affected Software(s): "Windows Meta File" (WMF) handler Impacted products Description Publication context: This Cert-IST alert informs you about the "WMF" flaw exploitation and more specifically of the spreading of SPAM e-mails or Instant Messaging messages that exploit the "WMF" flaw (CVE-2005-4560). Reminder : The vulnerability concerns the "Windows Meta File" (WMF) image handling. It may allow a remote attacker, via a crafted "WMF" message, to execute arbitrary code on a vulnerable system. The information related to this vulnerability are available on the Cert-IST web site : Cert-IST advisory : AV-2005.485 Potential Danger : DG-2005.010 Crisis response hub : "Windows "WMF" Technical information: Unwanted SPAM e-mails are currently spreading. These e-mails exploit the new "WMF" flaw. They entice the user to browse malicious web sites, or contain as an attachment malicious images. Currently, there is for instance a "New Year" message spreading. It has the following characteristics : Subject : "Happy New Year", Body : "picture of 2006" Attachment : "HappyNewYear.jpg" If the user opens the attachment, the code runs and tries to download malicious code (Trojan horse for instance). Other messages (through MSN Messenger for instance) exploiting this flaw are also spreading. Solution Recommendations : Awaiting for an official Microsoft patch, the Cert-IST recommends to : Update your anti-virus solutions (clients and servers). Inform the users : not to open suspicious attachments (any image file and not only "WMF" extension), not to follow URL received by e-mails, or to browse suspicious web sites, to display e-mails in TXT format (brute text) in their mail client, not to use high privileges on their systems. Filter on your mail gateways HTML messages. Filter on your HTTP and mail gateways "image" files (extensions WMF, BMP, GIF, PNG, JPG, JPEG, JPE, JFIF, DIB, RLE, EMF, TIF, TIFF, ICO, etc...). Apply the temporary patch given in the Microsoft advisory (unregister the "shimgvw.dll" library). Implement a software restriction policy for blocking "shimgvw.dll" on Windows Server 2003 domain controllers. Update your IDS database signatures. Standard vulnerability IDs CERT/CC: VU#181038 Additional Resources "WMF" FAQ http://isc.sans.org/diary.php?storyid=994 Cert-IST Advisory https://wws.cert-ist.com/fast-cgi/AV/Avis.cgi?lang=eng&ref=CERT-IST/AV-2005.485 Cert-IST alert CERT-IST/AL-2006.001 https://wws.cert-ist.com/fast-cgi/AL/Alerte.cgi?lang=eng&Alias=cert-ist_al-2006_001 Cert-IST Crisis Blog https://wws.cert-ist.com/fra/hub/windowswmf/ Cert-IST Potential Danger CERT-IST/DG-2005.010 https://wws.cert-ist.com/fast-cgi/DG/Danger.cgi?lang=eng&Alias=cert-ist_dg-2005_010 Microsoft security bulletin MS06-001 http://www.microsoft.com/technet/security/Bulletin/MS06-001.mspx Vulnerability evolution http://www.f-secure.com/weblog/ http://isc.sans.org/ History Version Comment Date 1.0 Alert creation 02 January 2006

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