Virus warnings: Watch out for latest Bagle and Mytob

Email and internet users are being urged to look out for the latest variant of the Bagle family of malware which has started "spreading like wildfire" according to one security vendor.

Also a new variant of Mytob has been spotted in the wild.

MessageLabs claims to have intercepted around 70,000 instances of the as yet unnamed Bagle variant during a three hour period on 31 May, with 45,000 being intercepted between 15:00 (BST) and 16:00 (BST). Other vendors are yet to recognise its spread, suggesting caution rather than panic is the order of the day.

According to MessageLabs the virus appears to have originated from a Yahoo! group.

The email appears to offer little by way of social engineering with a blank subject line and no body text judging by those intercepted so far by the UK email security firm.

The Bagle downloader variant drops a Trojan which will attempt to download Bagle from a long list of locations. It also has a self-propagating element bundled into a zipped attachment. When activated it will harvest email addresses and send itself on to all contacts on an infected user's machine.

According to Blackspider, Mytob has been seen in slightly smaller numbers but is yet another infection for users to be wary of. Many of the subject lines used by the 60KB email refer to imminent closure of the user's email account. It also carries a zipped attachment.