Microsoft confirms NT security flaw

Microsoft Corp. today acknowledged a security flaw in its Windows NT operating system that could allow a person to access protected files on a workstation or even deny users access to a Windows NT server.

The bug surfaces at an embarrassing time for the software maker. The company is scrambling to address privacy concerns raised earlier over a feature in its Windows 98 operating system that allows Microsoft to compile a hardware profile of users when they register their software.

The vulnerability in NT is exploited by running a malicious program when a system is in screensaver mode, a Microsoft product manager confirmed. The program can elevate the user’s log-in status to that of an administrator, giving him or her access to protected files in the computer.

“We’re developing a fix for the problem and we’ll have the patch available by the end of the week,” said Scott Culp, security product manager at Microsoft. The patch will be posted on the Web at, he said.

The flaw was discovered by an Indian software firm, Cybermedia Software Private Ltd., and affects all versions of Windows NT including two beta versions of Windows 2000 (formerly known as Windows NT 5.0). The problem will be fixed before Windows 2000 is released commercially, Microsoft’s Culp said.

“This vulnerability requires that a person be able to log on to a system locally, that they can actually put their hands on the keyboard. It’s not something you can exploit over the Internet,” Culp said.

Exploiting the vulnerability on a workstation would give a user access to protected files on that machine, he said. Since most workstation users already have administrator status on their own machines, the issue is largely moot, he said.

On a Windows NT server, Culp acknowledged that the hack could allow a user to become a “domain administrator,” empowering him or her to read protected files elsewhere on a network and to deny clients access to the server. However, standard security procedures at corporations prevent non-administrators from logging onto servers, Culp said.

“The primary vulnerabilities are in workstations and terminal servers,” he said, adding that the hack takes a lot of skill and would constitute a “sophisticated technical attack.”

Microsoft has an e-mail address set up where users can report suspected security issues — which is how Cybermedia alerted Microsoft to the Windows NT problem, Culp said. “Microsoft takes security seriously; we know it’s important to our customers,” he said.