Microsoft Windows users faced widespread exploitation of another unpatched buffer overflow this week. Days later, there is still no patch. Defenses include antivirus updates, making sure no user opens any wmf attachment, and better IPS filters.
One would think that after nearly two decades, Microsoft could find and remove the buffer overflows in the code it distributes to tens of millions of people.
Alan
@RISK is the SANS community's consensus bulletin summarizing the most important vulnerabilities and exploits identified during the past week and providing guidance on appropriate actions to protect your systems (PART I). It also includes a comprehensive list of all new vulnerabilities discovered in the past week (PART II).
******************************** SPONSORD LINKS ********************************
1) Join us for a Free SANS Webcast "Migrating from WEP to WPA2" Wednesday, January 04 at 1:00 PM EST (1800 UTC/GMT) http://www.sans.org/info.php?id=973
2) Earn your Masters degree in Information Security Engineering, from SANS. www.sans.edu
3) SANS 2006 (Orlando, Feb 24 - March 2) Deadline for early registration is January 4. http://www.sans.org/sans2006
********************************************************************************
Part I is compiled by Rohit Dhamankar at TippingPoint, a division of 3Com, as a by-product of that company's continuous effort to ensure that its intrusion prevention products effectively block exploits using known vulnerabilities. TippingPoint's analysis is complemented by input from a council of security managers from twelve large organizations who confidentially share with SANS the specific actions they have taken to protect their systems. A detailed description of the process may be found at http://www.sans.org/newsletters/cva/#process
Description: A Windows metafile (WMF) is a 16-bit file format to store and display graphics, which is supported on all Windows platforms. A 0-day buffer overflow vulnerability has been reported in the "SHIMGVW.DLL" library responsible for processing Windows metafiles. A malicious webpage, shared folder or an HTML email containing a specially crafted metafile can exploit the buffer overflow to execute arbitrary code on a Windows system. Exploit code has been publicly posted. The flaw is being actively exploited to install spyware and Trojans on client systems. F-Secure reports detecting 57 different malicious WMF files in the wild so far.
Status: Microsoft is aware of the problem. However, no patches are available as of now. The anti-virus companies have updated their signatures to detect the malicious WMF files as well as malware that is installed a successful exploitation. Please update the AV software and re-scan your systems. Network-based Intrusion Prevention/Detection systems can be used to block the download of malicious WMF file via HTTP/SMTP/SMB etc. Another suggested workaround is to unregister the SHIMGVW.DLL. Steps for this are outlined in the SANS Handler's Diary. Even while using Firefox/Mozilla browsers, users should decline to open a WMF file when prompted. Council Site Responses: The great majority of council site systems will obtain the update through the public Microsoft Update site, or through their local WSUS server, whenever Microsoft happens to release a patch for this.
Council Site Actions: The one site that responded stated they have just a few web sites using phpBB that are directly exposed to the Internet. Theses sites are not used for critical applications and are not supported by their central IT department. They have not seen any compromises from this exploit, and suspect that the PHP versions and configurations are different from what the exploit requires.
This list is compiled by Qualys ( www.qualys.com ) as part of that company's ongoing effort to ensure its vulnerability management web service tests for all known vulnerabilities that can be scanned. As of this week Qualys scans for 4750 unique vulnerabilities. For this special SANS community listing, Qualys also includes vulnerabilities that cannot be scanned remotely.
(c) 2005. All rights reserved. The information contained in this newsletter, including any external links, is provided "AS IS," with no express or implied warranty, for informational purposes only. In some cases, copyright for material in this newsletter may be held by a party other than Qualys (as indicated herein) and permission to use such material must be requested from the copyright owner.
==end==
Subscriptions: @RISK is distributed free of charge to people responsible for managing and securing information systems and networks. You may forward this newsletter to others with such responsibility inside or outside your organization.