Win32/Bagle is a family of mass-mailing worms that targets certain versions of Microsoft Windows. The worm spreads primarily through e-mail, though some variants also spread through peer-to-peer networks. The worm acts as a backdoor Trojan, allowing an attacker to access a computer that it has infected. The backdoor can be used to distribute other malicious software. Some variants of Win32/Bagle infect executable files.