Trust No One, Monitor Everyone?

The so-called Zero Trust model for security proposed by Forrester Research earlier this month has revived debate about the way organizations secure their networks.

Zero Trust means end users are no more trusted than outsiders, and that organizations must inspect all traffic, from the outside and on the inside as well. While this concept has stirred Big Brother worries among skeptics, it also resonates with some experts in light of the end user application-borne attacks as well as malicious or careless insiders.

But does this user threat trend merit a whole new security model? Most security experts agree that you can't trust your internal network and have to assume you've been compromised, so it's a matter of detecting and stopping breaches before any information is stolen or damage is done. It's just that inspecting all internal traffic can be a tall order -- and maybe overkill.

Zero Trust means inspecting all traffic in real-time and adding a new generation of network analysis tools that blend forensics, packet capture, metadata analysis, and network discovery flow analysis and would work with security information management systems, according to John Kindervag, senior analyst with Forrester, who first presented the model at Forrester's recent Security Forum.

Kindervag says the existing trust model in security is broken and that the answer is to eliminate the idea of a trusted internal network and untrusted external network. All network traffic is untrusted, he says. The idea is to weave security into the network fabric, he says.

"By flipping the model to verify, but never trust, we can completely change the paradigm of how we do things. We have to be willing to think differently," Kindervag says.

There will "absolutely" be user pushback, he says, "but we have to know what's going on in our networks."

Eric Cole, CTO of the Americas at McAfee, says the basic idea of Zero Trust is nothing new in that it assumes an enterprise has been attacked, so you need to know what is happening in your network. "They are pushing more of a granular approach, but looking at everything won't scale [in large organizations]," he says.

"The trick with Zero Trust is don't go granular. Do more correlation, look for generic anomalies, go in and understand what is the normal amount of packets, the average size and time of a connection, [and] the average number of encrypted links going out," Cole says. "You develop the top five to 10 anomalies and compare them over days, and the system will keep bubbling up the ones you want to pay close attention to."

Not all traffic should be considered equally untrusted, says Fred Kost, director of marketing for Cisco security. There are different levels of trust in the network, and different zones, he says. "Not all are untrusted. There are areas that may be more locked down," he says.

It's akin to the borderless network concept, where end users aren't all in the office and behind the firewall, but instead are working remotely, from their iPads or other consumer devices, for instance, he says. You need more context with their roles, Kost says, in order to set up what users are allowed to do on the network.

Monitoring all traffic could be overwhelming. "That's a lot of data," he says. "Each company has to decide how much it makes sense to monitor and what doesn't make sense to monitor."

This more flattened network requires more than another layer of defense-in-depth, according to the Zero Trust model.

Marc Maiffret, CTO with eEye Digital Security, says a combination of defense-in-depth and zero trust is needed. Layers of security make it tougher for the bad guys to sneak in from the outside, but sophisticated, targeted attackers always find a way in, he says.

"Here you're looking at the internal communications of the network and behaviors on the desktop and monitoring that more closely," Maiffret says. That shouldn't raise any major privacy red flags, he says, because this is what organizations need to do to thwart attacks.

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