T 5.7 Interception of lines

On account of the small risk of detection, interception of lines is a threat to IT security that must not be neglected. Normally there are no tap-resistant cables. Only the necessary effort differs for an interception of different cables. Whether a line is being intercepted can only be determined with a great expenditure of measuring technology.

A decision to intercept a line will, essentially, depend on whether the obtainable information would be worth the technical (financial) expenditure and the risk of being detected. This question can only be answered if the attacker's individual possibilities and interests are taken into account. Therefore, definitive identification of the targeted information, and thus of the lines which might be intercepted, is not possible.

Examples:

• Thus, for instance, it is wrong to assume that messages sent by electronic mail are the equivalent of letters in the classical sense. As E-mail messages can be read throughout their way through the network, they can be compared more realistically to postcards.

• Some manufacturers supply, together with their operating systems, programmes for the debugging of networks, which, however, can be used for data interception as well