Win32/Dumaru is a family of mass-mailing worms that targets certain versions of Microsoft Windows. The worm sends itself as an e-mail attachment to addresses that it finds on the infected computer. The worm runs when the user opens the attachment. Some variants drop a backdoor Trojan. Win32/Dumaru can infect or overwrite files, open ports, connect to an IRC server, release passwords and other confidential information, and receive commands from attackers.