Phishers are developing highly sophisticated methods of targeting high-level executives and wealthy end-users, creating bogus messages that are more convincing than ever before, researchers warn.

The practice of targeting specific organizations or users with false messages ("spear phishing") isn't new. But with practice, phishers are getting better at researching their targets to find the wealthiest and most influential people online -- a practice sometimes called "whaling." And now, they also are using that research to social-engineer messages that are hard to ignore.

"For example, we've seen messages recently that not only call the user by name, but make reference to specific pieces of real estate that the individual owns," says Andres Kohn, vice president of product management at Proofpoint, which researches spam and phishing attacks in support of its messaging security tools.

"In many cases, those references will be made in a message that appears to come from a major government agency or authority, such as the Department of Justice or the IRS," Kohn says. "The phishers will also give the message a sense of immediacy, something the reader needs to act on right away, and a link. When you combine all of those things, it's easy even for a savvy user to be fooled into clicking on the link."

These links usually lead to a convincing-looking Website that extracts further personal data from the user, or it might contain a Trojan or keylogger that enables the attacker to damage or steal information from the user's machine, he says.

To add to their veracity, some phishers now also include a phone number in their message, Kohn reports: "It used to be that phishers never used phone numbers, because they are easy to trace. Now, some of them are using voice-over-IP numbers that can be easily taken down and are difficult to trace."

Users who call the numbers sometimes get an automated system that prompts them to give up additional personal information, Kohn says.

Proofpoint's high-level email security package is designed to help enterprises identify and block sophisticated phishing messages before they get to the user, according to Kohn.

Another security vendor, Iconix, also was talking about the problem of sophisticated, targeted phishing attacks yesterday. "Consumers are being targeted more precisely by cyber criminals with personalized phishing attacks that are increasingly convincing," said Jeff Wilbur, vice president of marketing at Iconix. "Even the latest filters and email authentication checks used by email providers don’t catch all forms of phishing."

Iconix is attacking the "whaling" problem from the sender's side, rather than the recipient's side. In a nutshell, the Iconix Truemark service uses industry-standard technologies such as DKIM, Domain Keys, SPF, and SenderID to verify the authenticity of the sender's message. Then it checks the identification of the email sender against its list of registered senders.

Once an email has passed through these steps, Iconix attaches a Truemark Check-lock icon to the message, verifying that it is a legitimate communication from the sender. If the user has signed up for the service, which is free for recipients, the icon is displayed on the message in the user's inbox.

Iconix has already signed up about 500 sender companies for its service, including Paypal, which announced an agreement with Iconix yesterday.

No matter what defenses they choose, however, enterprises are likely to see an increasing number of whaling and spear phishing attacks coming to their top-level executives in the weeks to come.

"We're definitely predicting an increase in tax-themed attacks as we get deeper into tax season," Kohn says. "We'll see a lot of messages purporting to be from the IRS, as we do every year, but we'll also see a lot of messages that appear to be coming from the online tax services. As more people handle their taxes online, that's a new approach for the phishers."

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