A love letter in your inbox might make some senders blush. Twenty years ago, however, an e-mail message with the subject line "ILOVEYOU" was actually not so sweet. The love letter had a virus attached to it that caused billions of dollars in damage. Twenty years later, the author of the unlovely virus admitted that he had unleashed the malicious code.

According to the author of the virus, also known as the "Love Bug," he did not intend for it to cause so much damage. No, there was no damage at all, according to BBC News writer Jeff White, who tracked down the culprit at a cell phone repair store in Manila. His name is Onel de Guzman, now 44.

Guzman claims to have written an earlier virus for the purpose of stealing Internet passwords for dial-up connections. He explains that ILOVEYOU is based on that virus he wrote earlier, but adds the ability to send itself to the person's Outlook contacts. According to Guzman, he first targeted the login information of users in his area because he could not afford Internet access at the time.

The wider net proved tricky and costly; according to CNN, ILOVEYOU was on track to lose $10 billion at its peak. Some estimate that the economic impact would be even greater. It is difficult to break down why it took such an economic hit, but it probably has to do with the cost of removing the virus, restoring affected files and systems, downtime to deal with the disruption, and even general security enhancements. Either way, it hit large corporations like Ford and government agencies around the world. [According to CNN, Guzman's lawyer said at a press conference on Sunday, "He doesn't recognize that the actions that were imposed on him were really done by him. So if you ask him if he was aware of the consequences, he would say he was not."

In a blog post, security firm Sophos described how the virus worked, explaining that the payload was contained in a Visual Basic Script file disguised as a benign text file. This was in the early days of webmail. Once clicked, the malicious file was busy overwriting and infecting other files on the victim's PC, including images (JPEGs) and music files (MP3s). In addition to e-mail, it sometimes attempted to spread via IRC, an instant messaging protocol that became popular in the early 2000s

.

This raises an interesting question that Guzman has not addressed much - if the intent of his first virus was simply to steal login information for Internet access, why did ILOVEYOU overwrite files that had nothing to do with it? While his interview with the BBC does not provide a direct answer, it seems he just wanted to see how far it would spread. Guzman "made the title of the e-mail attachment globally appealing and tried to tempt people around the world to open it." ...... De Guzman claims that he first sent the virus to someone in Singapore and then went out drinking with friends. De Guzman first learned of the global mess he had unleashed when his mother told him that the police were chasing hackers in Manila.

Since the advent of ILOVEYOU, the malware business has changed dramatically, but the basic concepts remain the same. And 20 years later, Windows still hides file extensions unless they are manually configured to show them. This makes it easy to disguise files, for example, by making a malicious executable file look like a normal document or image.

As for Guzman, he escaped punishment because it was not illegal in the Philippines at the time.