A lack of standards has opened up holes in corporate networks that can be exploited by hackers, according to a presentation at this week's Black Hat security conference.

Larry Greenemeier, Contributor

August 3, 2006

3 Min Read

While there's strong agreement that network access control should be a part of any corporate security strategy, all agreement ends when it comes to defining what exactly NAC is and how different vendors' interpretations of the technology will work together.

This confusion has opened up holes in network access control technologies that can easily be exploited, one security vendor said Wednesday at the Black Hat USA 2006 conference.

The concept behind NAC is relatively straightforward: Don't let any devices connect to your network unless they pass muster by complying with your company's security policies. "It's a valid technology and something you need to consider as part of your network security," said Ofir Arkin, chief technology officer and co-founder of Insightix Ltd., a maker of NAC software used to monitor network traffic and probe devices as they attempt to connect.

Yet even though Insightix has a dog in the NAC fight, Arkin's Black Hat presentation focused more on what's lacking in NAC and how these omissions could be very dangerous to businesses deploying the technology.

In theory, NAC technology should include the ability to:

- detect devices trying to connect to the network;

- authenticate the identity of the device's user;

- check whether the device has the proper level of anti-virus protection and software patches to comply with corporate security policy;

- enforce corporate policy by sending the device to a network quarantine for remediation;

- and provide continuous monitoring for security problems once the device is connected.

Still, there isn't any one NAC provider that offers all these capabilities, which means companies must use multiple NAC technologies that aren't necessarily designed to work together.

Also, companies that deploy NAC using a Dynamic Host Configuration Protocol proxy server to assess a device's compliance with a company's security policies can run into several problems.

In particular, only devices that use DHCP to communicate information about their settings and characteristics can be assessed by the DHCP proxy server. Any devices not using DHCP are either blocked or must be added to a list of exceptions that the NAC system will automatically allow onto a network unchecked. A DHCP configuration also can't be extended to include remote users, Arkin added. NAC vendors also rely on the IPSec and 802.1x protocols, but none accommodate all three.

Another NAC shortcoming is that devices afflicted with a zero-day virus or worm with no known fix can't be remediated and allowed onto the network. Arkin also expressed concern that attackers could target systems in quarantine and infect them with malware. Once those systems are given the proper software patch and anti-virus updates, they would be allowed onto the network and not rechecked.

Some of the major networking and access control technology makers have taken steps toward compatibility, but don't expect seamless integration anytime soon. Cisco, currently the biggest player in the NAC market, still requires its Network Admission Control technology to work only with Cisco networking equipment.

Others are promising to be a bit more flexible. Cisco rival Juniper Networks in May announced that its Unified Access Control technology will support the Trusted Computing Group's Trusted Network Connect, or TNC, open standards, a set of nonproprietary specifications for the application and enforcement of security requirements for endpoints connecting to a network.

The TNC specifications are designed to help network administrators enforce security policies for network access in environments that include a variety of devices running a variety of software. Microsoft's Network Access Protection, or NAP, will show up in Windows Vista and in Longhorn server, but customers will have to implement both before they can benefit from the NAP system.

On a smaller scale, Lockdown Networks on Monday said its Enforcer NAC appliance will provide endpoint health check, quarantine, and remediation capabilities that work with the AEP Networks' Netilla Security Platform SSL virtual private network.

Until these technologies all get on the same page, however, network access control software and appliances will stand in their own way of success.

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