Microsoft admits flaw in Windows 2000 server software

Microsoft Corp. on Tuesday acknowledged that an "extremely serious" flaw in an obscure extension included in Windows 2000 could allow a hacker to gain complete control of any system running both Windows 2000 and the company's Internet Information Services (IIS) 5.0 server.

The bug, which affects Windows 2000 Server, Windows 2000 Advanced Server and Windows 2000 Datacenter, is due to an error in an extension which enables the Internet Printing Protocol, a feature installed by Windows 2000 that allows for the submission and controlling of print jobs over HTTP (hypertext transfer protocol). Because of an error in the coding of the ISAPI (Internet Services Application Programming Interface) extension which implements Internet Printing, a hacker can send a certain kind of data to any server running Windows 2000 and IIS 5.0, cause a buffer overflow, and take full control of the system through ISAPI, the company said.

Microsoft has made available on its Web site a patch that fixes the problem. It is "imperative" that anyone running IIS 5.0 apply the patch, said Scott Culp, program manager of Microsoft's security response center. The flaw is extremely serious, he said, because once exploited, any program can be run as part of the operating system and take control of the operating system. "There is literally nothing a program could not do," he said.

The hole was first reported to Microsoft 10 days ago by security-product vendor eEye Digital Security. Microsoft has worked with eEye to verify and repair the problem, Culp said, adding that eEye "handled this exactly right." Information about the vulnerability and the patch have been posted on Microsoft's Web site and information has been distributed to hundreds of thousands of Microsoft users, partners and customers, Culp said.

Though the flaw is serious, it will only affect those who have explicitly enabled Internet Printing, Culp said. In setting up IIS 5.0, users are told to disable any unneeded components, were given automated options to doing so and were also presented with an option to lock-down any components not explicitly enabled, Culp said. Anyone who has followed these procedures and not enabled the Internet printing extension should be fine, he said.

The bug reported Tuesday is only the latest in a series of high-profile flaws in Microsoft Internet products. In mid-April, the company's ISA Server was found to be vulnerable to a denial of service attack and in late March, holes were found in the company's Exchange 2000 and Internet Explorer products.