The email attack, which occurred over two days in the last week involved spamming numerous variants of the Bagle virus in a systematic attack. The levels of new viruses reached such levels that Finnish antivirus company F-Secure broke its record for new viral definitions in one day.
"This is the second massive email attack phase from this hacker in two days - the creator is obviously intent on infecting as many people as possible," said Carole Theriault, senior security consultant at antivirus company Sophos. "Businesses should consider blocking all executable code from entering their networks via email - most companies have no need to receive computer programs via this route, and it dramatically reduces the risk of infection."
The emails typically arrive with some reference to the word "price" and come from an as yet unknown source.
According to Antivirus company Kaspersky at least 20 new versions have been detected over the last week.
Over the last 12 months Bagle has remained on top of the viral charts. In November last year SC reported virus increased over 100 percent in only 24 hours due to the virulence of the Bagle AU worm. An unusually high number of variants caused a large upturn since the virus was first detected in October.