WiMax's Small Steps to Security

Sprint Nextel Corp. (NYSE: S)'s decision last week to spend $3 billion on a new high-speed wireless network gear catapulted WiMax right into the public eye. But what Sprint didn't talk about -- and is less well understood -- is what security measures will protect users who move over to the broadband wireless network. (See Sprint Goes WiMax.)

Analysts, industry experts, and operators are expecting to see some of the same kinds of attacks undertaken against the older 802.11 WiFi standard used against its younger sibling. "I expect we'll see similar problems with [WiMax] as we've seen with other devices, namely weak management protocols and vulnerable applications -- embedded Web servers, unencrypted access via telnet and SNMP V1 and V2," says ex-Tipping Point security consultant Shawn Merdinger.

Security will become a bigger issue with WiMax and other high-speed wireless services, if enterprise experience with WLAN technologies is any indication. Access and authentication remain key wireless concerns for enterprise buyers and users.

There is, however, an increasing awareness that wireless's weakest link may not be in the security methods used to protect it, but rather in the insecure coding at the software driver level, which can be exploited by clever hackers.

"I don't think WiMax is any less secure than WiFi or cellular, both of which I think are secure," says Ken Dulaney, VP of mobile computing at Gartner Inc. "You will probably see some attacks, but I warn everyone who claims it's a WiMax failure to see whether the problem results from other areas," whether faulty drivers or something else, Dulaney says. WiMax and WiFi are both borne of the same orthogonal frequency-division multiplexing (OFDM) technique, he adds.

John Larson, research scientist at Sprint Labs, says gaining access to a device via faults in its drivers is one type of attack that concerns Sprint. Similar hacks at the recent Black Hat security show demonstrated how easily malicious types could gain access to an unsuspecting user's laptop using such drivers. "That's exactly what I'm thinking about," says Larson. "One of the things we really need to do is make sure we work with our vendors on that."

Waiting on Profiles

In fact, the requirements for a complete wireless security system are not even covered by the basic specification. The 802.16 standard -- and hence WiMax -- only defines the air interface and the PHY (physical) and MAC (media access control) layers. This still leaves work to be done on security and network-to-network communications.

Little, if any, of this ambiguity is slowing down equipment makers. "Standards still seem to be a moving target in this area, but plenty of vendors are rolling out gear already," says security consultant Merdinger. "It should be interesting to see how well this early gear operates down the road."

The IEEE standard says that data being broadcast over the airwaves must be encrypted. The fixed wireless standard 802.16d uses the Advanced Encryption Standard (AES).

Meanwhile vendors are still discussing the Extensible Authentication Protocol (EAP) methods that could be used with mobile WiMax. "It's not yet been agreed on," says Dave McGinness from the CTO organization at Sprint Nextel.

When they first find and connect to a new WiMax network, devices will send out a "manufacturer's certificate" to assure the network that the device is what it appears to be. From what Unstrung has seen and heard, vendors and operators will likely have to work together to implement more complicated certification systems for applications like e-commerce.

"We feel like we have a really good toolkit, but it's the implementation of that toolkit that counts," says McGinness.

Indeed, this has been a constant issue with WiMax, simply because the standard offers a smorgasbord of options within the specification that could be implemented. This has already led to the suggestion of interoperability problems between the fixed and mobile specifications. (See WiMax: A Spec Divided.)

Since official Mobile WiMax products are not even on the market yet it's hard to gauge exactly the level of concern about WiMax security. The Sprint WiMax network will start to be switched at the end of 2007 but the big push will come in 2008.

— Dan Jones, Site Editor, Unstrung