Ten years ago today, on May 4, 2000, a security team with MessageLabs, a provider of messaging security services, came in to work and discovered the number of viruses its system had intercepted in the last several hours was off the charts.

MessageLabs security team was the first to stop and name LoveBug, a mass-mailing worm later reckoned to have infected 45 million computer users worldwide. As a result of the malware outbreak the percentage of viruses in email surged overnight from just one in every 1000 emails to one in 28 on 4 May 2000. Email servers worldwide ground to a halt under the onslaught.

Infected messages appeared as messages from contacts of an intended mark with the subject line "ILoveYou", and an infected attachment called "LOVE-LETTER-FOR-YOU.TXT.vbs". Crucially, a security shortcoming of the time means the final .vbs extenuation was hidden by default from Windows users, who were therefore easily duped into thinking the email contained only an innocuous txt file attachment.

Users tempted to open these infected message attachments were exposed to a Windows-based malware payload that harvested email addresses from compromised machines and sent out more infected messages, continuing the spread of the worm. The worm used infection routines written in VBScripts, helping to popularise a technique that was then comparatively unusual.

Evidence from the malware pointed the finger of blame for the creation of the worm towards Filipino student Onel de Guzman, who was arrested and quizzed by police but escaped prosecution because of a lack of relevant cybercrime laws in the Philippine at the time. Computer hacking laws were rushed through Parliament in the Philippines and introduced weeks after the outbreak in July 2000, but weren't backdated, allowing de Guzman to avoid prosecution.

The LoveBug, and the less successful but nonetheless virulent Melissa worm that preceded it, marked the heyday of mass-mailing worms that used social engineering trickery to spread. Such attacks are now very rare with targeted Trojan attacks and botnet clients now the mainstay of the threat environment. In some way the LoveBug recalls an earlier, more innocent, age before cybercrooks and state-sponsored parties took over the scene.

To mark the anniversary MessageLabs, now Symantec hosted services, commissioned an artist Alex Dragulescu to create an image of the malware. The resulting image - which looks a bit like a pollen seed.

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