I-Worm.Invalid

Worm Invalid spreads by e-mail in messages with infected executable attachments. It is designed to trick a user: the letter with an attachment imitates the Microsoft security advisory. If a user executes the attachment, the worm installs itself to the computer and distributes its copies using a remote mail server. It also has a dangerous payload: if an infected messages were not sent due to some errors the worm corrupts all executable files, so almost all software will be unusable and the infected PC will fail on next startup.