Undisclosed Flaws Undermine IT Defenses

Computerworld - Attacks targeting software vulnerabilities that haven’t been publicly disclosed pose a silent and growing problem for corporate IT. But responses to such threats have been largely misguided because of misconceptions about them, according to some analysts and security vendors.

So-called zero-day exploits are generally defined as attacks that target publicly known but yet to be patched vulnerabilities. The dangers of such attacks are obvious, said Alan Shimel, chief strategy officer at StillSecure, a vendor of network security software in Superior, Colo. But, Shimel said, it’s equally important that companies be prepared to deal with undisclosed vulnerabilities, or “less-than-zero-day” flaws, that are unknown to anybody but attackers.

Typically, such flaws are discovered by security researchers only after they have been successfully exploited by attackers, Shimel said, adding that companies tend to continue relying on patches to address security problems instead of putting multilayered defenses in place. “It’s time to put the emphasis back on the unknown attacks out there,” he said.

Hard to Block

In most cases, blocking such attacks is very hard because of the fact that the vulnerabilities are unknown, said John Sullivan, chief technology officer at Atlas Group Inc., a Kennebunk, Maine-based telecommunications consultancy. “Someday you’re going to miss something, and someone is going to get in using an exploit no one knows about,” Sullivan said.

Therefore, the emphasis has to be on detecting and containing the fallout from any attacks to the greatest extent possible, he added. That requires multiple layers of defenses not just at the network perimeter but behind it as well, according to Sullivan, who recommended the use of security measures such as strong user and device authentication, strict role-based access controls, network segmentation and data encryption.

Beyond Patches

Users and analysts give the following tips for defending against less-than-zero-day attacks: •  Focus on early detection via network traffic analysis and behavior-modeling tools. •  Use "whitelisting" approaches to keep out all but approved applications and online services. •  Emphasize damage control via network segmentation, plus strong access controls and user and device authentication.

Robert Bagamery, a system support specialist at a large Canadian utility that he asked not be named, said it’s also a good idea for companies to have a tightly controlled “whitelist” of approved Web sites and Web-based applications for their end users. IT managers should restrict access “to only necessary and dependable sites,” he said.

Gartner Inc. analyst Amrit Williams said much of the confusion about what constitutes a zero-day threat stems from the manner in which some security vendors have used the term when pitching their products. “Whatever nomenclature is used, there is a whole class of basically unknown exploits taking advantage of unknown vulnerabilities,” Williams said.

But the reality is that most organizations “aren’t experiencing pain” from less-than-zero-day attacks, he added. For now, the biggest pain point for IT managers continues to be publicly disclosed flaws for which no patches are available, according to Williams.

One well-known example was the Windows Metafile flaw that Microsoft Corp. disclosed and hurriedly patched early this year. “Most companies don’t know how to deal with situations where patches don’t exist,” Williams said.

Read more about Security in Computerworld's Security Topic Center.