Researchers said they've uncovered an active campaign that has already stolen more than $1 million using a combination of malware and social engineering.

The Dyre Wolf campaign, as it has been dubbed by IBM Security researchers, targets businesses that use wire transfers to move large sums of money, even when the transactions are protected with two-factor authentication. The heist starts with mass e-mailings that attempt to trick people into installing Dyre, a strain of malware that came to light last year. The Dyre versions observed by IBM researchers remained undetected by the majority of antivirus products.

Infected machines then send out mass e-mails to other people in the victim's address book. Then the malware lies in wait. A blog post published Thursday by IBM Security Intelligence researchers John Kuhn and Lance Mueller explains the rest:

Once the infected victim tries to log in to one of the hundreds of bank websites for which Dyre is programmed to monitor, a new screen will appear instead of the corporate banking site. The page will explain the site is experiencing issues and that the victim should call the number provided to get help logging in. One of the many interesting things with this campaign is that the attackers are bold enough to use the same phone number for each website and know when victims will call and which bank to answer as. This all results in successfully duping their victims into providing their organizations’ banking credentials. As soon as the victim hangs up the phone, the wire transfer is complete. The money starts its journey and bounces from foreign bank to foreign bank to circumvent detection by the bank and law enforcement. One organization targeted with the campaign also experienced a DDoS. IBM assumes this was to distract it from finding the wire transfer until it was too late.

The success of the Dyre Wolf campaign underscores the need for improved training so employees can better spot malicious e-mails and suspicious ruses like the one involving the phone call to the targets' banks.