5 years ago: Melissa variant upgraded to high-risk category

06.12.99: The Melissa variant, ExploreZip.worm.pak, is hitting corporate America hard and can now be classified as an 'outbreak', according to one leading security vendor.

The virus spreads through Microsoft Outlook email like its predecessor.

According to Network Associates' laboratories, the virus has moved from medium- to high-risk status and companies should download updated security software as soon as possible.

06.12.04: The devastating original Melissa virus outbreak in early 1999 was the original 'modern' virus and its impact made home users and businesses alike wake up to the damage malicious code was capable of.

Apart from the many variants such as the one above spawned by Melissa, it represented the start of a huge rise in the number and seriousness of self-propagating worms with the ability to spread rapidly. In more recent times we have seen the likes of the Love Bug, Klez, MyDoom, Sasser and Blaster.

The Melissa virus writer was eventually caught in 2002 and sentenced to 20 months in prison, although recent punishments for these kind of crimes have been somewhat more lenient.