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Patch Tuesday Bottomline – December 2009

Microsoft closes 2009 with its last regular patch release adding 6 bulletins bringing the year’s total to 74. December’s release is by our current standards a rather normal workload of 12 individual vulnerabilities. As expected Bulletin MS09-072 fixes the critical 0-day Internet Explorer vulnerability that was publicly disclosed just 3 weeks ago. Microsoft credits iDefense for the vulnerability, so it appears that they had been working on the issue already. Still Kudos to the team at Microsoft for the quick release. This patch is rated for immediate deployment as attackers are actively working on making the POC into a reliable exploit. The advisory further contains an additional 4 vulnerabilities, with 3 affecting Internet Explorer 8, including Windows 7. BTW, this is the only bulletin this month that affects Windows 7 and Windows 2008 R2.

Bulletin MS09-070 deals with remote code execution on Active Directory on Windows 2003 and 2008. This is rated as Important because it requires an attacker to be authenticated. If the attacker has credentials, an exploit can be used to execute code on the active directory server and impact core infrastructure of corporate environments – we recommend fixing it as quickly as possible after internal testing.

MS09-073 and MS09-074 address vulnerabilities in file formats for Word/Wordpad converters and MS-Project. Both allow remote code execution when users open specifically crafted files that can be received through e-mail or downloaded from a website. Install the patches as quickly as possible and review whether extended testing is necessary in your environment.

The 2 remaining bulletins MS09-069 and MS09-071 address the Windows operating system, one in the well-known LSASS component and the other in the Intenet Authentication Services (IAS). The LSASS is a resource consumption DOS only vulnerability and the IAS only affect Windows 2008 with MSCHAP v2 enabled. The exploitability index for both is 2 and we think these patches should be installed as necessary.

The highly critical vulnerability in IE6/7 with an exposure window to exploits of over 3 weeks without the availability of a patch, should put the task of getting users off IE6/7 on the top of IT admins New Year’s resolutions for 2010. They have to be migrated to a more modern browser, with the most viable options being IE8 with its well known patching mechanism or Firefox 3 with its more aggressive patching schedule.

Outside of the direct Microsoft realm, Adobe will release an update for a critical Flash vulnerability that we recommend installing right away.

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