Microsoft announced last week a new system for rating the severity of security holes in its software. But it also urged the security community to exercise better judgment about publicizing software vulnerabilities and detailing how they can be exploited.
The practice of publishing explicit, step-by-step instructions for exploiting vulnerabilities contributed to the damage that was inflicted on users of Windows-based systems by recent worms such as Code Red and Nimda, said Scott Culp, manager of Microsoft's Security Response Center.
But several users said that while Microsoft had raised a valid and long-standing issue, the company itself is to blame for many of the security problems affecting its software.
"The problems are most certainly not caused by full disclosure. They're caused by bad coding practices," said Josh Turiel, network services manager at Holyoke Mutual Insurance Co. in Salem, Mass.
In a note published on Microsoft Corp.'s Web site last week, Culp lashed out at the "information anarchy" that "allows even relative novices to build highly destructive 'malware' " using published information about vulnerability exploits.
People who make such information available have argued that it can help systems administrators figure out how to protect their systems. But Culp said in an interview that Microsoft's investigations of worms such as Nimda, Code Red and Sadmind clearly showed that those worms used exploit techniques similar to ones that had been detailed publicly in some cases, they employed even the same file names and exploit code.
As a result, it's better to tell users only what systems are affected, how they're affected and what can be done to plug the holes, Culp said. For example, Microsoft said its new severity rating system is meant to give users a better idea of the risks posed by different vulnerabilities (see box).
Leaving specific examples of exploit code out of vulnerability information is generally a good idea, Turiel agreed. But, he added, "the danger, as I see it, is that if someone discovers a flaw and it's not repaired or disclosed to the public, how do we defend against people who know about it?"
David Lelievre, a project manager at Tweddle Information Services Inc., an application service provider in Clinton Township, Mich., said the notion that "a systems administrator should bury his head in the sand and install patches without knowing what they are going to actually do to the system is ridiculous." A mere lack of published information is "not going to prevent the next wonder kid from writing a virus," he added.
With that in mind, Microsoft should focus on fixing the vulnerabilities in its software, not on criticizing those who publicize exploit information, said David Krauthamer, MIS manager at Advanced Fibre Communications Inc., a maker of telecommunications equipment in Petaluma, Calif.
However, Daniel McCall, an analyst at Waltham, Mass.-based security consultancy Guardent Inc., said Microsoft does have a point.
"Our view is, don't tell people how to break a system," McCall said. A far better approach would be to release vulnerability information only after a fix has been developed, he said. Guardent's policy is to inform vendors and other relevant parties when holes are discovered and then wait until patches are available before publicizing the flaws.
New Rating System Gets Fast Workout
Microsoft got a chance to use its new vulnerability severity rating system almost as soon as it was put in place. But the process was temporarily marred by a faulty patch.
Last week, Microsoft warned users of a moderate risk vulnerability affecting terminal servers using Windows NT 4.0 or Windows 2000 on corporate intranets. For deployments on external Web servers, the risk is low, the company said.
The denial-of-service vulnerability affects the Remote Data Protocol implementation that's included with the terminal service in the two operating systems, according to a security bulletin on Microsoft's Web site.
Rebooting a server that has failed because of the vulnerability will restore the system, but any work in progress at the time of the attack would be lost, Microsoft said. It recommended that users install a patch meant to plug the hole.
But more than 30 users reported that the patch itself caused system problems, according to the NTBugTraq mailing list. Microsoft pulled the patch from its Web site and said a new version would be released "shortly."