Lirva (w32.Lirva@mm), also known as Naith, is a mass-mailing worm that is UPX-compressed to a file size of 32,766 and arrives via e-mail either announcing a new Microsoft patch or offering fan access to Avril Lavigne. Once active, Lirva will attempt to e-mail copies of itself to all contacts on an infected system, shut down all antivirus and firewall programs, and launch a Web browser to open the Avril Lavigne Web site on an infected user's desktop.

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