Vulnerability of IEEE802.11 WLANs to MAC layer DoS attacks

Previously, WLAN security issues have focused upon flaws in the WEP encryption and authentication processes. There exist, however, vulnerabilities in the lower layers of the protocol stack that may be easily exploited to produce denial of service attacks. One area to exploit is the medium access control (MAC) protocol that aims to ensure availability and fair sharing of the available wireless bandwidth. The fact that existing security mechanisms, such as encryption and authentication (including the proposed 802.11i standard), are not sufficient to prevent such attacks means that these vulnerabilities are of particular significance. In addition, the attacks may be crafted such that a limited degradation in service occurs, resulting in a reduction in the performance of the network, without the obvious signs of a traditional denial of service attack that could be detected by users or the network administrator. It is worth noting that the attacks require only standard IEEE802.11b hardware and software. This presentation exposes the WLAN MAC layer vulnerability and presents experimental results for the degradation in service caused by a variety of attack methods. The advantages of these attacks over traditional RF jamming are also explored. The discussion and conclusions highlight the challenges of securing and protecting the evolving wireless network infrastructure.