If you receive an e-mail warning you that a virus or spyware has been detected on your system, just delete it.
That's the warning coming from the Internet Storm Center after the virulent Storm worm morphed from last week's Fourth of July greeting into this latest trick this week. This time, there is a different subject line and different text, but the same potential infection.
"As per usual, discourage users from blindly clicking links in e-mails," wrote Mark Hofman, a handler at the Internet Storm Center, in his blog. "Educate them on your corporate [antivirus] and [anti-spyware] practices, so they will know that the message is not legit. And even if you do block all these messages, maybe raise awareness with staff so they don't fall for these types of messages at home. Blocking downloads of .exe files is also a good start."
The Australian Computer Emergency Response Team (AusCERT) issued a warning on Monday that researchers there had spotted high volumes of spam trying to spread the Storm worm. The Australian CERT group reported seeing e-mails giving users phony warnings of viruses and spyware, as well as an older Storm worm scam that lured users with promises of phony e-card greetings.
"A user visiting the links contained in these e-mails is prompted to install malicious software," wrote AusCERT researchers in the alert. "This software contains backdoor functionality to allow a remote attacker to fully control a system. ... Currently, this malware is not well detected by many anti-virus vendors. AusCERT has observed more than 50 sites hosting this malware."
Last week, the Storm worm authors tried to use the Fourth of July holiday to spread their malware. They sent out waves of spam with subject lines about the holiday and the country's 231st birthday. And just days before that, security researchers were warning users about a spike in the number of spam e-mails that were enticing users into going to malicious Web sites where their machines were infected with a variant of the Storm worm. That particular scam used messages about phony e-card greetings that were supposedly waiting for the unsuspecting users.
The worm, which appeared in January, raised its ugly head with various spam schemes in February and then April, as well. The April outbreak used a trick similar to this week's scam, sending out e-mails with subject lines like "Worm Alert," "Virus Alert," and "Worm Activity Detected."