Microsoft has released an über-patch that aims to address all the previously announced vulnerabilities in its IIS Web server software, and a few more besides.

The cumulative patch includes the functionality of all security patches released to date for IIS 5.0, and all patches released for IIS 4.0 since Windows NT 4.0 Service Pack 5.

Microsoft has promised that the cumulative patch eliminates the "side effects" of the previous IIS cumulative patch, which have led some admins to defer the installation of the fix even while the FBI warned the Russian Mafia was exploiting flaws with IIS to raid online banks.

Apparently it took the outbreak of Code Red for Microsoft to take anything approaching decisive in making its easier for admins to guard against the many flaws on IIS.

The update, which amounts to a point release for both IIS 4 and IIS 5, also addresses five previously undisclosed vulnerabilities with IIS, which could result in either denial of service or privilege elevation.

• A denial of service flaw that could enable an attacker to cause the IIS 4.0 service to fail, if URL redirection has been enabled. The Code Red worm generates traffic that can in some cases exploit this flaw even on boxes that weren't susceptible to infection by the worm.
  
• A flaw with the WebDAV feature of IIS 5.0 that could temporarily disrupt services.
  
• Yet another DoS bug that revolves around the IIS 5.0 interprets content containing a particular type of invalid MIME header.
  
• A buffer overrun vulnerability involving the code that performs server-side include (SSI) directives. An attacker who had the ability to place content onto a server could include a malformed SSI directive that would crash a system and insert potentially malicious code into the system, where it might subsequently be executed.
  
• A privilege elevation vulnerability involving the processing tables used by IIS 5.0.
  

That's quite a list and it makes you wonder what other bugs the notoriously flaky IIS harbours.

When Microsoft next releases a Web server product we hope it sees the value of a comprehensive security audit BEFORE the product is released. We can but hope... ®

External Links

MS bulletin: cumulative patch for IIS

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