Researchers have detected a new phishing attack that promises to enhance the security of the user's emailbox -- and then downloads a malicious Trojan instead.

The email requests that recipients click on a link in the body of the email to update the "security mode" of their emailboxes, according to researchers at Red Condor, an email security tool vendor.

Users who click on the link are taken to a Website that advises them to update to the latest version of the Macromedia Flash Player by downloading "flashinstaller.exe." This executable is actually a banking Trojan that is known to disable firewalls, steal sensitive financial data, and provide hackers with remote access capabilities, Red Condor says.

The malware is more commonly known as Win32:Zbot-MGA (Avast), W32/Bifrost.C.gen!Eldorado (F-Prot), PWS-Zbot.gen.v (McAfee), or PWS:Win32/Zbot.gen!R (Microsoft), the researchers note.

The spam campaign was detected late on Nov. 20; within the first six hours, Red Condor says it blocked more than 500,000 email messages. So far, the company says it has stopped more than 3.5 million messages belonging to this campaign.

"Protecting inboxes is seen as business-critical, so it is no surprise that spammers and cybercriminals are playing off of email users' growing security concerns with security-focused junk mail," says Tom Steding, president and CEO of Red Condor. Hours after the spam campaign began, only about half of the antivirus products had begun to recognize and block it, Steding says.

"Spam that suggests users update their Flash Player is a common type of scam during the holidays, but it is often associated with viewing a fake e-card or a viral video," Steding observes. "We encourage email users, particularly those returning to full inboxes after the Thanksgiving holiday, to immediately delete these messages and notify their IT administrators."

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