Autorun-Related Malware Declines and the June 2011 Security Bulletin Release

Hello there. First off, I’d like to share some news regarding the updates we made to the Autorun feature in Security Advisory 967940, which we released in February 2011. The advisory made changes to how Autorun handles “non-shiny” media (eg., USB thumb drives). The change was expected to make a significant difference to infection rates by malware that uses Autorun to propagate, and we’ve been monitoring those rates ever since.

The initial results are encouraging. As of May 2011, the number of infections found by the Malicious Software Removal Tool (MSRT) per scanned computer declined by 59 percent on Windows XP machines and by 74 percent on Windows Vista machines in comparison to the 2010 infection rates on those platforms. (Windows 7 had the updated Autorun settings built in by default.) For more details and statistics regarding the drop in Autorun-abusing malware infections, please see the Microsoft Malware Protection Center (MMPC) blog.

As we previously mentioned in the Advance Notification blog on Thursday, today we are releasing 16 security bulletins, nine of which are rated Critical, and seven of which are rated Important. There are four Critical-level updates that we want to call out as top priorities for our customers in June:

  • MS11-042 (DFS). This bulletin resolves two privately reported issues affecting all versions of Windows.
  • MS11-043 (SMB Client). This bulletin resolves one privately reported issue affecting all versions of SMB Client on Windows.
  • MS11-050 (Internet Explorer). This security bulletin resolves 11 privately reported issues in Internet Explorer.
  • MS11-052 (Windows). This bulletin resolves one privately reported issue in Windows and is also Critical.

We recommend that customers apply these and all other updates as soon as possible.

In this video, Jerry Bryant discusses this month’s bulletins in further detail, focusing on these four bulletins:

As always, we recommend that customers deploy all security updates as soon as possible. Below is our deployment priority guidance to further assist customers in their deployment planning (click for larger view):

The Security Research & Defense team has further information on deployment priorities for today’s bulletins on their blog.

Meanwhile, our risk and impact graph shows an aggregate view of this month’s severity and exploitability index (click for larger view):

Since we’ve started specifying separate Exploitability Index ratings for the current and the earlier versions of products affected by each vulnerability, it’s easier to see how individual vulnerabilities affect newer products versus older ones. We assign Exploitability Index ratings solely to Critical- and Important-severity vulnerabilities, and there are 32 of those this month (the others are Moderate-level issues in MS11-050). Of those, 14 vulnerabilities have a lower Exploitability Index rating for the latest-and-greatest version of the software than for the older version, or the latest version isn’t affected at all. The remaining CVEs have no difference in severity between the versions.

More information about this month’s security updates can be found on the Microsoft Security Bulletin Summary web page. Also this month, Microsoft is increasing MSRT detection capabilities for three worm families — Win32/Rorpian, Win32/Yimfoca and Win32/Nugel. Please see today’s MMPC blog for more information.

Per our usual process, we’ll offer the monthly technical webcast on Wednesday, June 15, hosted by Jerry Bryant and Jonathan Ness. We invite you to tune in and learn more about the June security bulletins, as well as other announcements made today. The webcast is scheduled at 11 a.m. PDT, and the registration can be found here.

For all the latest information, you can also follow the MSRC team on Twitter at @MSFTSecResponse. Also feel free to tweet the hash tag #MSFTSecWebcast and ask any questions you may have regarding the bulletins before Wednesday at 11am PDT. We’ll answer as many questions as possible live during the webcast.


Angela Gunn
Trustworthy Computing.