Microsoft Updates August 2013

Critical Internet Explorer across All Windows Clients, OpenType Font Parsing, Exchange OWA Vulnerabilities Fixed

Today, Microsoft released a set of eight security Bulletins (MS13-059 through MS13-066) for a broad variety of vulnerable technologies and exploit categories. The critical vulnerabilities are not known to be exploited publicly at the time of Bulletin release. The more interesting Bulletins this month address RCE and EoP vulnerabilities in Internet Explorer, Windows components, and yet again Exchange/OWA components licensed from Oracle. Also included in this month's release are fixes for RPC, kernel drivers, Active Directory, and the networking stack.

MS13-059 is the priority update to roll out across Windows clients, as it fixes nine critical memory corruption vulnerabilities (that look like use-after-free to me) in IE6, IE7, IE8, IE9, IE10 and even IE11 preview on Windows 8.1 preview, along with XSS due to flawed Kanji font handling and flawed code in the "Windows Integrity Mechanism", which is used for sandboxing apps like Internet Explorer, Adobe Reader and Google Chrome. On Windows server, the maximum severity is "Moderate" and doesn't effect "Server Core" installations at all. Admins need to refer to the severity ratings and maximum impact table to prioritize server patch deployments, but those that need to prioritize patch deployments probably shouldn't surf the web from these types of systems anyway.

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MS13-060 corrects code in the Unicode Scripts Processor implementing OpenType font handling, a format developed by Microsoft and Adobe over the past decade built on top of the TrueType format, in USB10.dll. This dll is used by Windows and all sorts of third party applications to handle right-to-left scripts like Arabic and Hebrew, and other complex fonts like Indian and Thai scripts too. The vulnerability is a user mode vulnerability that effects only Windows XP SP 2 and 3 (64 bit too) and Windows 2003 versions. These types of systems continue to be widely deployed, especially in government and critical infrastructure systems around the world. Exploits may be delivered via spearphish, as in the Duqu incident, or via a web page for a browser like Internet Explorer, as in Duqu copycat malcode like the Blackhole exploit pack that continues to be widely distributed and highly active.

Another interesting update includes MS13-061 that patches code in third party components built by Oracle and licensed by Microsoft for Outlook Web Access on Exchange Server 2007, 2010, and 2013. Applying the patch will not require a system reboot, but it will restart related Exchange services. The interesting thing about this critical set of issues is that they enable exploitation of the WebReady Document Viewing and Data Loss Prevention features on OWA for code execution not on the client system, but on the server itself with LocalService credentials. So a client system browsing code sent to their email account can remotely execute code on the server in the service's context, which is very problematic.

Please review the set and update ASAP. While most of the vulnerabilities this month were privately reported, these present high risk opportunities and the Exchange issues and exploitation are publicly known.

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