Ferreting Out Rogue Access Points And Wireless Vulnerabilities

For almost 18 months starting in 2005, attackers used wireless networks at TJX and other retail chains to steal credit card data. The vulnerabilities were not an isolated instance: Subsequent research found that about half of all retail outlets in one shopping center had insecure wireless networks.

Today, WiFi security has improved somewhat, but insecurities in installations still remain far too common. Vulnerability assessments of more than two dozen companies found a quarter have rogue wireless access points that were installed by employees, and a third of their wireless networks had misconfigurations that undermined their security, according to wireless security firm AirTight Networks, which conducted the tests.

"A rogue AP is a very serious problem if you have it -- an unmanaged, unknown device that is circumventing your defenses," says David King, CEO of AirTight. "All the layers of defense that you worked so hard to put in can be circumvented by a single device that is communicating in the clear."

Following the breaches at TJX and other retailers, the Payment Card Industry started requiring quarterly scans of wireless networks. It's likely it will increase the requirement to monthly scans, King says.

Companies that use wired-only scans are missing half of the picture, he says. Vulnerability scanning on the wired network could pick the wireless routers, but it won't find insecurities in the wired network.

"If you think about [wired-only scanning], that's goofy -- it doesn't make any sense," King says. "In the case of the TJX hacker, you wouldn't have found any of that."

The need for better wireless security analysis has led companies, such as AirTight, to build their businesses on wireless versions of intrusion detection systems and intrusion prevention systems -- so-called WIDS and WIPS.

"If you do scanning to get compliance, there is a requirement in the spec that you have to scan. You have to have alerts and have a corrective action plan," he says.

While vulnerabilities in wireless networks are common, wireless attacks are a far less common occurrence. Between 2004 and 2006, 13 percent of cases investigated by the incident response teams at Verizon Business involved improperly secured wireless networks. Yet the teams only found a single incident involving wireless networks as a vector in each of the following three years. In 2009, the breach occurred because of a rogue access point.

Companies should go beyond just relying on the wireless network's encryption, such as WPA2 or the weaker WPA, and instead use a strong virtual private network technology, such as IP security (IPSec), says Marc Maiffret, chief technology officer for eEye Digital Security.

"Your wireless network could be using WPA2, but the attackers could eventually figure out a way to break that," he says. "Encrypting your connections is another layer of defense."

Another common vulnerability in wireless networks is caused by misconfiguring guest access, Maiffret says. The corporate wireless network uses wireless encryption, such as WPA2, and per-user authentication, but the guest network is either configured so that a visitor could access corporate IT assets, or it sits behind the same router as the rest of the network.

Both situations could help an attacker, he says.

"They throw it between the Internet access point and their main router, but now if that access point is compromised, you can sit there and sniff everything going out of the company," Maiffret says.

Companies should keep the quest network completely quarantined from their corporate LANs, even going so far as to have a separate Internet connection for it, Maiffret says. "Make sure that it is truly separated," he says. "We suggest that people not even put the guest network on their main Internet link, but on a backup link."

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