Examination of information in transit. Examples include
telephone tapping, network tapping, and I/O buffer watching.
Complexity: Except in cases where cryptography, spread
spectrum, or other similar technology is used to defend against such an
attack, it appears that observation in transit over physically insecure
communications media is simple to accomplish and expensive to detect. In
cases where the media is secured (e.g., interprocess communication within a
single processor under a secure operating system) some method of getting
around any system-level protection is also required.