IPS: Still Playing Catch Up

Network intrusion prevention systems (IPSes) have taken plenty of heat for their limitations, but new products are still coming. (See IDS/IPS: Too Many Holes?)

Some non-traditional IPS vendors recently rolled out new products. Juniper Networks, for instance, added a new version of its Intrusion Detection and Prevention (IDP) software, version 4.1, for its IDP line that provides more visibility into the application-layer traffic. And Check Point officially released its IPS-1 IPS, a rebranded version of the product it inherited in its acquisition of NFR Security.

IPS devices are indeed getting more sophisticated, but they still aren't a replacement for any other devices at the perimeter, notes Michael Rothman, president of Security Incite. "In general, these IPS announcements are nothing new. NetScreen [for example, had] talked about deep-packet inspection since before the Juniper acquisition."

"IPS is becoming commoditized," says Thomas Ptacek, a researcher with Matasano Security.

Juniper's emphasis with its new IDP Version 4.1 is better visibility into, and control of, application traffic. "Port and source IP don't work anymore to enforce policy," says Sanjay Beri, senior director of product management at Juniper. "The IDP software upgrade... helps in discerning between enterprise IM and consumer IM. Folks are not just using IM but transferring files [with it], so this application-level [view] lets you take control [of the traffic]."

This would help you determine that Joe is on YouTube on his laptop, not just that he's running heavy HTTP traffic, according to Juniper.

Today's IPS products are still playing catch up when it comes to client-side vulnerabilities and file format issues, however, says HD Moore, director of security research for BreakingPoint Systems. "The only trend I see is an increase in the number of protocol decoders and stateful inspection systems, combined with an increase in performance."

Moore says another new feature for IPSes is the ability to determine which operating system is under attack, and to prevent the attack using that knowledge. But even that's old news technology-wise, he says.

And the trouble with "learning" type IPSes, he says, is that they provide hackers more options for evasion. "They open up even more ways to evade," he says. "[An attacker] sends just enough of one protocol string to make it think the port is something else, and then send the real exploit."

Ptacek says IPSes haven't proven that they're indispensable to the enterprise. "The reality is IPS just doesn't do much for enterprises," he says. "We've had the technology for coming up on 10 years now. Enterprises have had a chance to see whether their lives get simpler with IPS or not, and my perception is, most of them don't see a major change."

What about those enterprises that run both IPSes and firewalls? "If you ask most enterprise security teams, they'll admit they could remove all their IPSes and not suffer a major security incident because of it," Ptacek says. "They can't say that about firewalls."

But Spartaco Cicerchia, manager of network infrastructure for the Howard Hughes Medical Institute, which runs various Juniper products including its IPS systems, says he runs IPSes with his firewalls because firewalls alone aren't enough. It's all about layers, he says.

"It's important to understand where we put IPS -- both inside and outside," he says. "I always like to know who's knocking at the door, and if somebody got in. We have two different [IPS] hardware platforms that" do this.

Cicerchia says the ultimate goal is determining behavioral trends and making decisions on what to do with traffic based on abnormal behavior.

Meanwhile, Moore says IPSes work best for stopping known threats, enforcing policies, and basically keeping an eye on the network. "What they aren't good at is stopping dedicated or intelligent attackers," he says. "I consider them just another type of fancy firewall."

— Kelly Jackson Higgins, Senior Editor, Dark Reading