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When
May 4, 2000
Who
Onel de Guzman, a computer student in Manila, Philippines
Reach
Tens of millions of Windows PCs within days
Result
An estimated $10 billion in damage, and no jail time

An email nobody could resist

On May 4, 2000, people around the world got an email with the subject line “ILOVEYOU” and a note asking them to check the attached love letter. The attachment was named LOVE-LETTER-FOR-YOU.TXT.vbs. Windows hid the last part of the name, so it looked like a harmless text file. It was actually a small program.

Opening it overwrote files and mailed a copy to everyone in the victim’s Outlook address book, so the next email came from someone they knew. Starting in the Philippines, it infected tens of millions of Windows PCs within days and caused an estimated $10 billion in damage. Its creator, Onel de Guzman, was never jailed, because the Philippines had no law against it yet.

It didn’t break in. People opened the door. Most attacks today still start with someone clicking an attachment or link they weren’t expecting.

Don’t open the love letter

  1. Pause on unexpected attachments. Even from someone you know. If you weren’t expecting it, check with them by phone or text before you open it.
  2. Show file extensions in Windows. In File Explorer, turn on “File name extensions” so a file ending in .vbs, .exe or .js can’t pass as a document.
  3. Let your email filter the risky stuff. Attachment filtering, like Microsoft 365 Defender, blocks dangerous file types before they ever reach your inbox.

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