The virus, an email and peer-to-peer worm, turns off anti-virus applications, sends itself to email addresses found on the infected computer and drops malware on the system. It is also known as Bagle AT.
"There seems to have been a concerted effort to send out lots of variants over the weekend," said John Cheney, CEO BlackSpider. "It's been on the increase since its inception."
Within its code Bagle virus contains links to a number of compromised sites that originally seemed not to be active. This may no longer be the case. "It appears now that some of these links are active. Which is not as it was originally. Its aim seems to be to download and execute a trojan," said David Emm, senior technology consultant, Kaspersky.
But analysts think that Bagle is unlikely to become a major force, despite its recent upturn. In fact, some have suggested it merely highlights the age-old problem of home users not running sufficient anti-virus solutions. "Its not a huge problem yet," said Mikko Hypponen, director of anti-virus research, F-Secure.