Protection Against Rogue Wireless Access Points

Animesh Agrawal , M.Tech (WCC 1 st Sem),

Indian Institute of Information Technology


You have network access battened down, from Ethernet drops in the office to the VPN connecting remote sites and users. But someone, somewhere, has gained access through a wireless access point (AP) that you simply can't account for. You have a rogue on your network -- and you have a problem.

"Rogue APs are a problem particularly for companies that don't have a wireless policy," says Forrester Research principal analyst Ellen Daley. "While it won't exactly take down your network, it does pose a security threat.

There are, in fact, two kinds of rogue APs. The first and most familiar is the friendly rogue. These pop up when someone on the sixth floor heads out to Circuit City on his lunch hour, picks up a $50 wireless router and plugs it into the wall to make network connections more convenient in the accounting office. These kinds of rogue APs are friendly because they happen within the organization, and don't usually signal malicious intent.

"It gives access to the company network, and that can be a problem," Daley says. "But they're not usually as big a problem as they used to be. In the early days of wireless networking, they used to be much more common, but with the wide adoption of wireless, users are less motivated these kinds of unauthorized APs."

The other kind of rogue is the decoy or "evil twin" AP. Some digital miscreant sets up an AP of his own with a service set identifier that makes it look like it's a company access point. This certainly is malicious and though it doesn't give access to your network, it can give someone else access to your company secrets. Users confident that they're logging into the company site could unwittingly give away everything from passwords to corporate information.

The way you find rogue APs of either variety is to sniff them out. This can be a process as simple as popping open your laptop and seeing if something suspicious in the available networks dialog box, or investing in overlay systems to continually sniff the air for rogue SSIDs.

"The good news is that legitimate enterprise APs now have a built-in feature to intermittently sniff the air for rogues, so you don't necessarily need overlay equipment," Daley says. "That's pretty good for 90% of rogue situations. Most organizations are pretty good about sniffing the air and comparing MAC addresses with a database of authorized APs."

On the other hand, it wasn't always that way. Though self-sniffing APs are now the rule rather than the exception, there's a possibility that any company that invested in wireless networking back in the old says of even a couple of years ago, can't count on that kind of protection.

"The fat APs that were first rolled out in organizations didn't have that feature," Daley says "But they didn't provide much centralized control, and that market has begun to move to a more centralized model of wireless LAN suites."

The Need For Integrated Security :

The problem is that the replacement cycles are just starting now, so it's entirely possible that an organization that was in the first wave of wireless adoption isn't equipped to detect rogue APs. If the upgrade is still a while off, it might be wise to invest in sniffers. Above all, with wired and wireless networks becoming increasingly integrated, it makes a lot of sense to deploy intrusion protection systems (IPSes) to protect the whole network.

"Make sure that you consider wireless to be an integral part of your network and address security accordingly," Daley says. "I don't expect wireless to replace the wired network, but I do expect it to coexist, especially with VoWLAN (voice over wireless LAN). That means that you have to treat the network as a whole."

Even though it is often an afterthought to an organically grown wireless network, Daley says that a wireless policy is absolutely critical. "You have to define what your wireless policy is," she says. "Some companies simply say 'we don't allow wireless,' but that isn't a policy. It inadvertently allows wireless and invites users to set up rogue APs. You have to be realistic."

Finally, organizations need to have a strategy for Merging their wired and wireless networking policies. "This is really important," Daley says. "Because the networks will merge. You need to know how you are going to handle them in the future."