The Mytob worm is official top dog virus for this month. In fact, seven of the top ten virus positions this month were taken up by variants of this worm. Basically, 37 per cent of all viruses reported to Sophos in July stem from Mytob, making it a pretty successful piece of malware indeed.

'The Mytob army of malware is one of the biggest we have ever seen,' said Carole Theriault, a Sophos spokesperson.. 'The sheer volume and range of the Mytob worms sees them hog most positions in the virus chart. It's not the viciousness of the worm that is the problem, but the constant onslaught of slightly differing variants.'
The worm itself is also becoming more sophisticated; some variants now use techniques where an email message directs recipients to a website, where malicious code automatically downloads the Mytob worm.