WEP Remains Vulnerable

IEEE works to plug security holes; vendors, users try stopgap measures

Months after security vulnerabilities were found in the Wireless Equivalent Privacy protocol included with 802.11b wireless LAN technology, the IEEE and WECA are working to fill the holes and rebuild public confidence.

eWeek Labs believes current WEP offerings are adequate for securing data at smaller sites and home offices, with periodic WEP key changes. However, large enterprises with vital wireless data to safeguard should look to encryption alternatives now available.

Furthermore, although future versions of 802.11 security will be less vulnerable to hacks and easier to deploy, the Institute of Electrical and Electronics Engineers and the Wireless Ethernet Compatibility Alliance face an uphill battle to rebuild WEP?s popularity.

Both the IEEE, which helped develop the protocol, and WECA, which enforces interoperability among vendors, contend WEP was never intended to be a complete security solution but rather provides protection equivalent to that of wired networks. The IEEE has known about WEP?s vulnerabilities at least since October, and the IEEE?s Task Group E was charged with enhancing the 802.11 media access control layer to add security and quality-of-service features to the specification.

At a meeting earlier this month, the Security subgroup of Task Group E filed a request to break into a separate Task Group to expedite implementation of security enhancements.

WEP2 on tap

WEP2, which will likely be approved by the IEEE soon, will address some of the vulnerabilities by implementing a 128-bit IV (Initialization Vector) and 128-bit keys. But WEP2 is still based on RC4 encryption and the same IC (Integrity Check) value system (see list).

The WEP2 changes will alleviate the IV collision problem, but interoperable WEP key management and resolution to the IC vulnerability are not guaranteed in the near future.

These vulnerabilities are not the only problems in WEP. Officials at Cisco Systems Inc.?s Aironet division estimate that only one-third to one-half of their users deployed WEP before the vulnerabilities surfaced?which indicates a startlingly high number of users transmitting unencrypted data.

Currently, WEP relies on the use of identical static keys deployed on client stations and access points. Thus, key management becomes quite difficult as the number of clients increases.

Cisco has addressed this issue via its LEAP (Lightweight Extensible Authentication Protocol) for Aironet devices. As part of the log-in process, clients dynamically generate a new WEP key instead of using a static key. All clients have unique keys, which reduces (but does not eliminate) the risk of an IV collision.

IEEE Task Group E approved a draft to establish a similar interoperable authentication and key management system, tentatively called ESN (Enhanced Security Network). ESN marks the debut of AES (Advanced Encryption Standard) encryption and will likely not be part of 802.11 until next year. LEAP is intended to be interoperable with ESN.

Other 802.11 products provide encryption beyond WEP, but this protection generally comes at the cost of interoperability. Users can also deploy encryption wares that use virtual private networks, Secure Sockets Layer or Pretty Good Privacy, but this can mean large investments of time and money.