Microsoft has pushed out eight advisories as part of the August edition of its regular Patch Tuesday update cycle. With just three critical patches, the most interesting thing about this week's batch is the return of the "Ping of Death" in the form of a stability bug in the Windows IPv6 stack.
The critical updates offer new versions of IE and Exchange, as well as critical fixes for the soon-to-be-retired Windows XP. Collectively, this week's rollout covers 23 vulns.
The highest priority for patching is MS13-059, a cumulative update for Microsoft's browser software that fixes 11 vulnerabilities in all versions of IE – from IE6 to IE10 – including on Windows RT.
Redmond warns that creating exploits to attack unpatched systems would not be difficult, even though the flaws are yet to come under active attack.
A second critical update (MS13-061) addresses three vulnerabilities in Microsoft Exchange stemming from bugs in a third-party library, Outside In from Oracle, included in Redmond's enterprise-focused email server software.
Last of the critical batch is a security update for Windows XP (MS13-060). Windows XP loses support in April 2014, at which point there will be no more security updates. Up until then the soon-to-be-pensioned-off OS needs security updating like a Linux fan needs a date. The vulnerable Unicode Scripts Processor components patched by the update also appears in Server 2003.
The remaining five bulletins lower severity, and are all rated "important". Noteworthy in the quintet is an update that grapples with a Windows kernel vulnerability involving a flaw in address space layout randomisation (ASLR), a defence-in-depth measure, and a separate patch that tackles a stability problem in the Windows IPv6 stack that might easily lend itself to denial-of-service attacks against vulnerable networks.
Wolfgang Kandek, CTO of cloud security firm Qualys, said the flaw is akin to the type that facilitated the infamous late '90s vintage "Ping of Death" attack, which involved sending elongated packets to crash vulnerable web servers.
A few ICMPv6 packets with router advertisements requests can cause a denial-of-service vulnerability reminiscent of the famous "Ping of Death". It’s a good illustration of how much we still do not know about the stability of IPv6. We continue to recommend turning off IPv6 on workstations if your network is not engineered for its use.
The remaining three important bulletins cover "important" security bugs in Windows and Active Directory.
Ross Barrett, senior manager of security engineering at Rapid7, described the overall patch load this month from Redmond as "moderate".
"The August 2013 Patch Tuesday advance notification includes a slightly higher volume of fixes than last month, but only three of eight are critical, which is down from July’s six of seven critical fixes," Barrett said. "However, in a reversal from last month, the advisories are focused on Windows operating system patches, plus one Exchange issue." ®