Just weeks after re-issuing the cumulative browser update amidst a round of verbal jousting with a private security research company, Microsoft has again refreshed the patch to cover another code execution bug that could cause PC takeover attacks.
The flaw, which exists in the way IE handles long URLs when visiting Web sites using HTTP 1.1 protocol and compression, was flagged by eEye Digital Security, the same company that had its name zapped from the flaw credits when the update shipped for a second time on Aug. 24.
"We found another problem that they missed, even with the rerelease," said Marc Maiffret, chief hacking officer at eEye, in Aliso Viejo, Calif.
The latest bulletin credits eEye with finding the additional bug.
According to Tony Chor, group program manager in Microsofts IE team, the additional flaw was similar to the one that caused the original rerelease but actually existed in a different location.
"[With] the increased scrutiny this release received, a security researcher responsibly disclosed to us that a similar vulnerability was also discovered in IE5.01 on Windows 2000, IE 6.0 SP1 (in a different location), and the original release of Windows Server 2003 (not SP1). This rerelease fixes that vulnerability," Chor wrote on the IE Blog.
The embarrassing IE update episode underscores the challenges Microsoft, in Redmond, Wash., faces in shipping patches for multiple browser and operating system versions and strengthens the arguments from critics that the complex nature of the companys widely used software is a major security threat.
The September batch of updates also included a "critical" bulletin with fixes for a flaw in Microsoft Publisher, a program in the Office suite that allows users to create, customize and publish materials such as newsletters, brochures, flyers, catalogs and Web sites.
The Microsoft Publisher update—MS06-054—is the 25th bulletin covering holes in Microsoft Office. By comparison, for all of 2005, Microsoft shipped patches for five flaws affecting all versions of Office.
The company warned that an attacker could exploit the Publisher vulnerability using malformed strings in a specially created file.
Computer Terrorism, the research company credited with reporting the bug to Microsoft, said in an advisory that the vulnerable condition is derived from an attacker-controlled string that facilitates an "extended" memory overwrite using portions of the original Publisher file. "As no checks are made on the length of the data being copied, the net result is that of a classic stack overflow condition, in which EIP control is gained via one of several return addresses," the company said.
Computer Terrorism said it reported the bug to Microsoft more than 400 days ago.
The issue requires a certain degree of social engineering to achieve successful exploitation but users of Microsoft Publisher 2000 (Office 2000) are at an increased risk due to the exploitability of the vulnerability in a possible Web-based attack scenario.
Computer Terrorism, a research group based in London, is famous for releasing detailed exploit code for an unpatched IE bug in November 2005 after Microsoft misdiagnosed an earlier warning as a trivial denial-of-service issue.
The Patch Tuesday bulletin also includes MS06-052, an "important" fix for a flaw in PGM (Pragmatic General Multicast), the protocol used in Windows to enable receivers to detect loss or request retransmission of lost data. The bug affects Windows XP Service Pack 1 and Service Pack 2 and could be exploited by an attacker to gain complete control of an affected system.
A cross-site scripting flaw in the Windows Indexing Service is also fixed, with the MS06-053 update. Microsoft rated the issue as "moderate" and warned that an attacker could run a client-side script on behalf of a user to spoof content or disclose information.