Think layers of security is all that? Think again

Of 1,800 serious malware NSS Labs tested, some always managed to get through -- no matter what combination of protection was used

NSS Labs, a security research and advisory firm, has found that the layers of malware-catching technology that start at the perimeter of the corporate network and end at the desktop will always fail to catch some exploits.

In testing all the major technologies used by corporations, NSS found that some of the 1,800 serious malware it tested always managed to get through, no matter what combination of products was used.

In general, the typical layered defense comprises a couple of different firewalls, an intrusion prevention system (IPS), next generation firewall, security built into browsers and antivirus software on the desktop or notebook.

"Regardless of the number of layers I add into my security kill chain, things are still going to get through," said Frank Artes, research director of NSS. The term "kill chain" refers to the idea that malware missed by one layer will be caught, or killed, by the next layer.

All the malware used in testing various layers of technology had CVE numbers, meaning they were known exploits. Some were more than a half dozen years old, yet were still missed by the IPSes, firewalls, etc.

NSS did not research why each product missed a particular malware. In general, products fail because the malware's signature doesn't match what's inside the technology's database. The absence of a match is why malware variants and previously unknown exploit code gets through antivirus and other security software.

NSS has built a model in which subscribers can test many different combinations of technologies across several layers to see which malware got through. For companies looking to replace technology, the model is helpful in determining how their configuration will perform when the new products are used with existing technology.

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The NSS findings should not be seen as showing that layered technology is useless, however. "Layered security still makes the most logical sense," Artes said. "It's not performing as well as it should and that's because there's different layers of that security model where the vendors aren't producing what they've gone to market claiming they can do."

Security experts have pointed out the weakness of a defense-only strategy to many times before, and recently with the South Korea bank attacks. While firewalls, IPSes and antivirus software can catch a lot of malware, every corporation should assume that some malicious code has gotten through to infect systems.

With that, experts recommend monitoring hardware and software audit logs for abnormalities. In addition, systems where critical data is stored should be wrapped in their own security to prevent malware from penetrating. 

To improve layered defenses, Artes recommends making sure products are kept up to date and the latest malware signatures have been installed. In addition, companies should test vendors' products as rigorously as possible.

"We have products that come in for testing that perform all throughout the spectrum," Artes said. "Sometimes it's very eye-opening to the vendor themselves when they see how their produce performed when being actually evaluated."

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