In this attack pattern, the adversary intercepts information transmitted between two third parties. The adversary must be able to observe, read, and/or hear the communication traffic, but not necessarily block the communication or change its content. Any transmission medium can theoretically be sniffed if the adversary can examine the contents between the sender and recipient. Sniffing Attacks are similar to Adversary-In-The-Middle attacks (CAPEC-94), but are entirely passive. AiTM attacks are predominantly active and often alter the content of the communications themselves.