DoS is when an attacker disables or corrupts wireless networks, systems, or
services, with the intent of denying the service to authorized users. DoS
attacks take many forms. In most cases, performing the attack simply involves
running a hack, script, or tool. The attacker does not need prior access to the
target, because all that is usually required is a way to access it. For these
reasons and because of the great damaging potential, DoS attacks are the most
feared, since they are the most difficult to prevent.
Many DoS attacks
against 802.11 wireless networks have been theorized. One utility, called Wlan
Jack, sends fake disassociation packets, which disconnect 802.11 clients from
the access point. As long as the attack utility runs, clients are unable to use
the WLAN. In fact, any device operating at 2.4 GHz or 5 GHz can be used as a
DoS tool
.