Remote Windows NT, 95 features flawed

A Minneapolis firm has discovered multiple flaws in Microsoft Corp.'s use of an Internet Protocol that could lead to security breaches for remote access and virtual private network (VPN) users of Microsoft's Windows NT and Windows 95.

The flaws could allow a hacker to access passwords and private information and to crash a server, said Bruce Schneier, president of Counterpane Systems Inc., which discovered the flaw.

The problems result from Microsoft's use of the Point-to-Point Tunneling Protocol, which is designed to provide the security needed to create and maintain a VPN. VPNs use the Internet backbone as a channel for private communications by carving out a private tunnel using encryption and authentication technology.

"It's really kindergarten cryptography," Schneier said. "It's broken again and again and again. There's really no way to fix it. You have to turn it off. Network managers don't have a lot of options. They can either use it or not."

The flaws could affect Microsoft Windows NT and 95 users building remote-access and VPN solutions, said Wray West, chief technology officer of Indus River Networks, a supplier of remote-access VPNs. At least two other companies, Compaq Computer Corp. and RAScom, offer a Windows NT-bundled turnkey remote-access solution, he said.

Kevin Kean, Microsoft group product manager, said the flaws are "very theoretical and not likely to be encountered in a real-world environment." He also noticed that the PPTP vulnerabilities are being addressed with current and planned product enhancements. "Security is one of those technologies that continually moves forward. There will always be the next security enhancement to add to your product," Kean said.

Schneier said his company discovered at least five flaws, including weak algorithms that allow eavesdroppers to learn the user's password, mistakes that allow encrypted data to be read and a design flaw that would allow an attacker to masquerade as the server. He said he has notified Microsoft of the flaws.