Microsoft Patch Tuesday Targets More Critical Windows Flaws

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All five of the security bulletins in Microsoft Windows in September’s Patch Tuesday release are rated critical, including one that addresses a JavaScript engine vulnerability

Microsoft released five critical security bulletins late yesterday to cover issues in Microsoft Windows that company officials said could allow hackers to remotely execute code.

None of the vulnerabilities are known to be under attack at this time. Still, two of the bulletins address vulnerabilities that have been given the highest possible rating on Microsoft’s Exploitability Index, and security researchers recommend that administrators pay attention.

One is MS09-047, which deals with the way Microsoft Windows handles certain MP3 and ASF format files. The Windows component that processes MP3 files does not properly handle specially crafted metadata; likewise, the component that processes ASF files fails to properly handle specially crafted ASF files with malformed headers.

“We’ve seen similar exploits in the past and all a user would have to do is visit a compromised Website hosting one of these malicious files, which could be an MP3, WMA or WMV file, and they could become infected,” said Ben Greenbaum, senior research manager for the Symantec Security Response Centre.

This update covers Windows Media Format Runtime 9.0, Windows Media Format Runtime 9.5, Windows Media Format Runtime 11, Microsoft Media Foundation, Windows Media Services 9.1 and Windows Media Services 2008.

Another serious vulnerability lies in the way the JScript scripting engine processes scripts in web pages. When the scripting engine attempts to load the decoded script into memory to run it, it may trigger a memory corruption that can shut down Internet Explorer or lead to code execution. The vulnerability affects multiple versions of Microsoft’s operating system, including editions of Windows Server 2003 and 2008.

“MS09-045 is not a typical update from Microsoft and is particularly dangerous since it positions JavaScript as a weapon of choice by attackers,” said Josh Abraham, security researcher for Rapid7. “This is to be expected, since most of the vulnerability scanners are unable to help with JavaScript, giving attackers an incentive to look for more JavaScript-based methods. The activity on the attackers’ side with JavaScript is in stark contrast to the three years that have passed since the JScript bulletin that this update replaces.”

Both these bulletins have an Exploitability Index rating of 1, the highest such rating Microsoft gives out. Additional information about workarounds and mitigations can be found inside the bulletins.

The other vulnerabilities are a bug tied to the DHTML Editing Component ActiveX control, a vulnerability in Wireless LAN AutoConfig Service and several privately reported vulnerabilities in Transmission Control Protocol/Internet Protocol (TCP/IP) processing.

“A patch has not yet been made available for the Internet Information Services vulnerability made public last week,” Greenbaum noted. “Until a patch for this is issued, as a temporary workaround we suggest IT administrators using IIS 5.0 and 6.0 turn off anonymous write access immediately. We also recommend using a firewall and restricting access to creating directories. Those using IIS 7.0 with FTP Service Version 6.0 installed should upgrade to FTP Service Version 7.5.”