ILOVEYOU was the 2000 computer worm that spread through email attachments with the subject line “ILOVEYOU.”
The worm appeared in May 2000 and was distributed as an attachment named “LOVE-LETTER-FOR-YOU.TXT.vbs.” On systems configured to hide familiar file extensions, the extra “.vbs” could make the attachment look like a harmless text file. Opening it caused the Visual Basic Script to forward itself to contacts and overwrite or alter files.
ILOVEYOU spread rapidly because it exploited trust in personal email rather than a sophisticated network vulnerability. It affected millions of computers and caused billions of dollars in estimated damage, though published estimates differ because they include different categories of disruption and recovery costs.
It is often confused with Melissa, another major email worm from 1999. Melissa used a Microsoft Word macro, while ILOVEYOU was a Visual Basic Script email worm.