A new storm worm with an April Fool's Day theme is targeting the Web, according to security software firm PC Tools.

"The Storm worm gang has done it again. This time e-mails are being circulated, which are associated with the April Fool's Day theme," said PC Tools chief threat officer, Kurt Baumgartner.

The e-mail messages contain links that direct users to Web sites that contain malware. Once the files are downloaded and executed on the computer it sets a firewall exception rule and then attempts to "phone home" using various outgoing ports.

According to Baumgartner, the packer and major sections of executable code have changed significantly, indicating that it could be another variant and AV detection for this threat is close to nonexistent.

"The most effective way users can protect against these new threats is with antimalware products that use behavioral technology. Traditional AV products, which use signature detection are simply not equipped with this behavioral technology and the threat is currently evading those users' defenses," he said.

"Always exercise caution and don't just click on random links sent to your account via e-mail. Exercise even more caution when that random link is attempting to download a file to your system," adds Baumgartner.

PC Advisor is an InfoWorld affiliate.