File Quarantine is Mac users' first line of defense against malicious softwareWhile malware has long been an almost daily annoyance for Windows PCs, Mac users have become accustomed to not worrying about malicious software. Threats arise from time to time - in January of this year, for example, a Trojan horse made the rounds in pirated copies of Apple's iWork software -but most Mac users these days are probably running without virus protection software.