Antivirus company Network Associates has upgraded its rating of a new variant of the MiMail.I worm, which attempts to steal credit card information.

After being executed, the original MiMail.I code has been found to email itself out as an attachment with the filename 'www.paypal.com.scr'.

Network Associates warned that, due to an increase in the worm's prevalence, it has raised to 'medium' its risk assessment of the threat.

MiMail.I is the ninth variation of a threat that was first discovered in August.

The new variant bundles in social engineering in an attempt to steal credit card information from PayPal customers. It asks recipients to run the attached application, which then sends credit card information to four email addresses.

More information on the warning can be found here.