Blog: Microsoft Updates July 2013 - Serious flaws in IE, DirectShow and Multiple TrueType Font Handling Code Paths

As promised in Microsoft's July Advance Notification, Microsoft ships seven security bulletins this month (MS13-052 - MS13-058). At least 34 CVE are being patched. Six of the Security Bulletins are rated "critical" due to remote code execution issues. The vulnerabilities being fixed this month enable RCE across all versions of Windows operating systems, but most of these serious flaws have all been privately reported and there is no indication that they are publicly known or exploited yet. Some however, are publicly known and drew attention from a number of exploit developers.
The kernel mode vulnerability, CVE-2013-3172 is publicly known, along with another kernel mode bug publicly disclosed by Tavis Ormandy in May. Unfortunately, an exploit abusing that vulnerability was touched up by another contributor and then already integrated into metasploit for public distribution and use.
It's also interesting that the update for the kernel mode TrueType Font Parsing CVE-2013-3129 bug effects code paths in seven different software packages (Office, Lync, Visual Studio, .NET, Silverlight, and "Windows components") updated separately by Security Bulletins MS13-052, MS13-053, and MS13-054.

Internet Explorer receives the bulk of attention, with sixteen RCE bugs and one "information disclosure" bug all fixed up in one tidy bulletin, MS13-055. All of these but one are memory corruption issues, and all versions of IE across all operating systems are effected by one or another of these RCE issues.

Serious issues in multiple graphics components are being addressed this month.

Serious memory corruption flaw CVE-2013-3174 is being fixed in DirectShow that enables RCE across all supported Windows OS. DirectShow handles multimedia streaming, and the software mishandles .gif files, an ancient file format designed back in the day of 8-bit video, Windows 3.1 and x486. The major issue here is that this RCE exists across all versions of Windows.

A WMV decoding flaw is implemented in several dlls (wmvdecod.dll, wmvdmod.dll, and wmv9vcm.dll) that enables RCE. The dlls support Windows Media Player and the Windows Media Fomat Runtime across all versions of Windows except the server code installs. But, some administrators may have enabled the optional "Desktop Experience" and installed these dlls. These dlls are not all installed on each OS by default, so not all systems require MS13-056 DirectShow update.

TrueType font parsing, the software functionality attacked in targeted attacks including the Duqu campaign and currently a part of the Blackhole exploit kit, again enables exploitation of another vulnerability in kernel mode graphics handling component GDI+. This bug also exists across all versions of Windows.

The metasploit code attacking CVE-2013-3172 and patched with MS13-053 is currently limited to escalation of privilege, but with all the interest, this one may soon publicly become full RCE. Considering that the bug was publicly circulated in May, it is great to see Microsoft finally roll out a full patch for this one, because in addition to this month's TrueType handling fix, this win32k.sys vulnerability enables RCE across all versions of the Windows OS, including Windows 2012 core server installations.

.NET and Silverlight are being patched with one bulletin, and a couple of the bugs are publicly known.