Wireless networking technologies based on IEEE 802.11 series of standards are evolving to address many of the security issues that plagued earlier wireless standards. Unfortunately the current standards fail to authenticate management frames and network card addresses, and rely on loosely coupled state machines. This results in serious vulnerabilities that may lead to denial of service, session hijacking, and address masquerading attacks. Until the standards are updated to redress these problems, wireless network deployments must be supported by wireless intrusion detection systems–a challenging and under researched area. This paper presents techniques for improving detection of session hijacking attacks that are passive, computationally inexpensive, reliable, and have minimal impact on network performance. Experimental results are presented to give confidence in the utility of the techniques