(1) Detecting proprietary data being transmitted from the computer. Extrusion detection provides alerts, whereas "extrusion prevention" attempts to stop sensitive data from being leaked out. See
data extrusion.
(2) Detecting malware being transmitted from the computer. Extrusion detection is the opposite of "intrusion detection" (see
IDS), which looks for incoming malware. Extrusion detection software determines if a computer is generating the attack.