New variants of Bagel, MyDoom and Netsky flooded the internet as rival groups of virus writers sought to out-do one another. Anti-virus companies said the outbreak was more of a nuisance than a cause of any real damage to businesses, but warned security staff not to lower their guard.
"There is probably quite a bit of virus fatigue in IT departments. There is a danger that businesses will become complacent," said Natasha Staley, virus analyst at MessageLabs.
As Computer Weekly went to press 12 versions of Bagel, six of Netsky, and seven of MyDoom were circulating on the internet. With the exception of one version of MyDoom, which attempts to install a Trojan, none carry damaging payloads.