Harrenix.A is a Trojan that passes itself off as a video of the trailer of the film Harry Potter and the Order of the Phoenix in Italian. When it is run, an error message is displayed, which indicates that there has been an error and the video cannot be played.
While this message is being displayed, Harrenix.A downloads a variant of a dialer in the computer, detected as Dialer.KJD. Dialers usually try to establish phone connections with high rate numbers, significantly increasing the phone bill of the affected user.
Harrenix.A does not spread automatically using its own means. It needs an attacking user's intervention in order to reach the affected computer. The means of transmission used include, among others, floppy disks, CD-ROMs, email messages with attached files, Internet downloads, FTP, IRC channels, peer-to-peer (P2P) file sharing networks, etc.