Researchers Break Down NAC Defenses

If you think currently available Network Access Control technology is going to put that much-needed fence around your organization's most sensitive data, think again. A security research team says it has found ways to bypass all NAC systems, no matter which vendor makes them.

Researchers at Insightix, a security software vendor based in Ra'anana, Israel, later this month will show how they've broken the defenses of virtually every NAC vendor in a presentation at the Black Hat conference in Las Vegas.

"Each NAC product works a little differently, but in every case, we found the means to bypass it," says Ofir Arkin, CTO and co-founder of Insightix.

The vulnerabilities lie primarily in the way current NAC products are designed, Arkin explains. For example, most NAC technology assumes that users will be granted access to the network via Dynamic Host Control Protocol (DHCP), which keeps IP addresses in a pool and hands them out as each user is authenticated. Through DHCP, NAC systems can restrict user access and recognize unauthorized attempts to gain entry to sensitive information.

However, an insider with access to the corporate network often has the option to configure his PC with a static IP address, Arkin observes. With a valid IP address, the insider could effectively bypass all of the NAC controls and remain undetected by NAC defenses.

"All you really need is a user name and password, and you can do whatever you like," Arkin says.

The NAC market is dominated by heavyweights like Cisco, Juniper, and Microsoft, among others, like Check Point, Enterasys, and Symantec.

NAC systems are also at risk because they normally work entirely through IP addresses, without collecting information on where devices are located or how they are connected to the network, Arkin states. NAC systems generally cannot detect activity between nodes on the same subnet, particularly if the client avoids broadcast transmissions.

"That means if you can find the address of the router, which is contained in TCP/IP settings on most PCs, you can link directly to the router and enter the network undetected," Arkin says. Users could also gain access through unauthorized devices or old, forgotten systems and connections that don't show up in a standard DHCP address discovery.

Insightix has not found any examples of these exploits in the wild, but the approaches used by its research team could be easily reproduced by a company insider or by an attacker who steals even a single username and password, Arkin says.

Not surprisingly, Insightix is offering products that could help close the vulnerabilities in NAC systems. The Insightix NAC solution, introduced three weeks ago, includes a network discovery tool that not only shows DHCP addresses, but static IP addresses and details on how clients and devices are connected to the network.

"We can see all of the elements on the network and classify them, so that the [administrator] can find the elements that shouldn't be there," Arkin says. "A lot of users are surprised at the access points they find that they didn't know were there."

Arkin's full presentation, which will go through the NAC vulnerabilities on a vendor-by-vendor basis, will take place at Black Hat on Aug. 2.

— Tim Wilson, Site Editor, Dark Reading

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