T 4.60 Uncontrolled radio wave propagation

Wireless networks and the radio waves emitted often radiate beyond the limits of the rooms the networks are used in, and so it is possible for data to be transmitted to areas which cannot be controlled and secured by the users or the organisation. It is therefore possible to record the data with minimal effort, and this type of eavesdropping is only detected in a small fraction of all cases. The goal of such attacks may be to obtain or manipulate sensitive information. Due to the inadequate protection of many wireless networks, it is often enough just to record and analyse the wireless communications over a period of time even if the data is transmitted in encrypted form because the cryptographic key can be calculated afterwards using the data collected, and the transmitted data can then be decoded. Furthermore, directional antennas can be used to receive and capture data from the wireless network outside the limits of the network's specified range.

Example:

A laptop with a WLAN card, together with a few freely available WLAN applications, is all that is required to search for poorly secured WLANs. When wardriving, for example, people drive around a certain region, a city district, or a typical office environment with a WLAN client and record where and which WLANs are broadcasting and how poorly secured they are. In this case, the data can also be linked directly with GPS data to determine the geographic location of the WLANs found. Afterwards, poorly secured WLANs are targeted specifically, for example to gain free access to the Internet.