May 2, 2006

Three rules for safer Wi-Fi away from home

Author: Joe Barr

Almost everyone has heard about wardriving, the geek sport in which you drive around and see what wireless access points (WAP) you can find and access. Because of the ink wardriving has received over the years, many home and business users have wised up and added security to their WAPs. But how about the busy traveler, the exec at Marriott, or the slacker at Starbucks? Do they take that same level of care with wireless security while they're on the road and seduced by the easy availability of Wi-Fi hotspots? Probably not, but they should. Here are three simple assumptions you should make before taking your wireless laptop on the road.

Memorize these rules, understand what they mean, and learn what to do to protect yourself. When you can do that, you can begin to protect your private, confidential, and corporate data from inquisitive eyes.

  • Always assume someone is trying to see you enter a user ID or password.
  • Always assume that someone is reading every packet you send and receive by Wi-Fi.
  • Always assume that an "evil twin" is lurking near every Wi-Fi access point.

In following the first rule, don't worry about appearing to be rude or paranoid by moving the laptop screen position to block the view of your fingers as you're typing a password or user ID. Do the same thing to prevent those sitting to your right, left, or behind you on the plane, in the airport, or anywhere else from getting an eyeful of corporate secrets.

Act as if it is the most normal thing in the world to expect a little privacy, because it is, just as it is when you're entering your PIN at an ATM. Better than the above is not to do any of those things when you are close enough to others that they can see what you're trying to protect, even inadvertently.

While we're talking about physical security at the keyboard, password protect your laptop and set the timeout on your screensaver to a low number. Leaving your laptop behind in the hotel room while you go out for dinner or a meeting? Fine. Disconnect it from the network, power it down, and lock it.

The Wall of Shame

So much for point one -- on to point two. At Defcon each year, a group of attendees sniffs every packet sent and received via the wireless access points, looking for user IDs and passwords. Each time they find one, they unceremoniously add it to The Wall of Shame in public view. Just about the only thing easier than using a Wi-Fi network these days is intercepting the packets on it.

Avoid ending up on your own personal wall of shame by using only secure, encrypted connections to access your email, corporate accounts, financial data, and anything else of value. If your business or ISP provides Web mail, use it instead of unencrypted connections to POP or IMAP mail servers. A virtual private network between your laptop and headquarters or your home office is even more secure.

The bad guys will still be able to intercept every packet, but if they are protected by encryption, you're way ahead of the game. Most script kiddies stand about as much chance of cracking a recent WEP or WPA encryption scheme as they do of winning the Lotto. But there are others who will only be slowed down.

The evil twin

Finally, what about that intriguingly named evil twin? That's what security pros are calling a phishing scheme where the bad guys spoof a legitimate WAP's service set identifier (SSID), the name that differentiates one access point from another. Evil twins disrupt traffic to the authentic WAP and those associated with it lose their connection, then automatically re-associate with the device with the spoofed SSID.

You can avoid falling victim to this deception by not automatically attaching to a WAP and by not running your wireless connection in ad hoc mode. Know the SSID of the network you want to attach to, and learn what security options, if any, are available for it. Always use WEP or WPA instead of unprotected connectivity if you have that choice. If you can't, don't access sensitive data over the wireless connection, period. And finally, running a firewall -- the default behavior on most modern Linux distributions -- is a very good idea.

Your common sense is your best protection against losing confidential or personal data. Always behave as if the bad guys are really there, and that they really want all of your data. Acting on these assumptions is not a guarantee of wireless security, but following them will make you a lot safer than you would be otherwise.


  • Security
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