The University of SydneyPage 21There are bad guys (and girls) out there!–malware can get in host from:–virus: self-replicating infection by receiving/executing object (e.g., e-mail attachment)–worm: self-replicating infection by passively receiving object that gets itself executed–spyware malwarecan record keystrokes, web sites visited, upload info to collection site–infected host can be enrolled in botnet,used for spam. DDoS attacks