Second Cisco WLAN Security Threat Exposed: Page 2 of 3

Wright noted that LEAP is a "modified version of MS-CHAPv2 (which) is known to be weak, as documented in many sources."

Wright strongly advised LEAP users to take alternative measures.

"Customers using LEAP should be aware that the usernames and password of their user account are exposed, and should plan for the deployment of alternate authentication mechanisms such as PEAP or TTLS," Wright said in his posting. "Disabling user accounts after successive failed login attempts will not help protect against unauthorized access, since this is an offline attack that can be run at the attacker's leisure. At a bare minimum, LEAP users should immediately audit and expire user passwords that are based on dictionary words, or common derivations."

While this latest disclosure is unlikely to hurt Cisco much, it may hurt the continuing growth of wireless LANs, one industry analyst said.

"If Cisco responds appropriately and offer a fix, it shouldn't hurt them much," said Phil Solis, senior analyst for research firm ABI. "But it could hurt the progress being made in terms of people's perceptions of how secure Wi-Fi is."