Security researchers are warning about a variation of a "spear phishing" scam in which e-mails are sent to CEOs telling them they have been sued in federal court and must click on a Web link to download court documents, reports Computerworld.

The e-mails might have the CEO's name, company name and even phone number correct.

Said John Bambenek, a security researcher at the University of Illinois at Urbana-Champaign and volunteer at the Internet Storm Center:

For someone who doesn't know what a legal document looks like, it kind of passes the smell test. When they see they've been subpoenaed, people panic, and they click on things they shouldn't.

VeriSign's iDefense division warns it has tracked more than 1,800 cases in which the executive clicked on the link to the phony subpoena which redirects users to a malicious Web site. The Administrative Office of the U.S. Courts had posted a note to its Web site warning that the subpoenas are phony.