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rupting a frame as it was transmitted so that the receiver would drop it. The attacker
could then spoof an acknowledgement from the receiver saying that the frame was
successfully received. The sender would then delete it from the queue and the frame
would disappear from the datastream.
While DoS attacks don't allow an attacker to steal data or get access to the net-
work, it does create significant chaos to the network resources. It is very difficult to
stop and has disastrous consequences on affected networks.
4 . 4 M a n - I n - T h e - M i d d l e A t t a c k s
An effective man-in-the-middle (MITM) attack is one in which the attacker posi-
tions him/herself between the victim and the device with which the victim is trying
to communicate. In this capacity, the attacker can control the information between
the two devices. All traffic is re-routed through the attacker's computer where it can
be manipulated or simply inspected. The attacker can then gather login information
such as keys and passwords. In a wireless environment, the situation is more threat-
ening because information that is transmitted over a wireless network is by definition
available to all who have the ability to translate the RF signals to data. This might
involve the injection of malicious code into the datastream to further compromise of
the network and network nodes.
In the infrastructure mode of wireless networking, clients or stations all con-
nect to central access points. One MITM strategy is to spoof an access point by
de-authenticating and disassociating a client, neutralizing the AP with a DoS, and
then re-authenticating the client with a clone under the control of the attacker.
A number of MITM attack tools are widely available. Quite often the setup con-
sists of a software access point and DoS software. An attacker's computer would
usually have two separate wireless cards to handle both jamming and cloning func-
tions. Some of the software access point programs that are available are: HostAP
(
http://hostap.epitest.fi
)
and HermesAP (
http://hunz.org/hermesap.html
)
.
5.
Conclusion
It has been said that Wireless Networks will never be secure as long as radio
frequencies fail to observe property lines. The validity of this claim lies in the
fact that the physical security of the communication technology is for all intents
and purposes absent in wireless environments (cf. also
[9]
). Though the physical
security of a building is not a fault-proof barrier, it is at least a practical one. Wire-
less technology, even if properly configured, is not even a practical barrier. Even
the most risk-averse can “sniff” transmissions with little chance of detection by
using free software that is easily found on the Internet. The plain truth is that
