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Bogus IRS beefs become latest scammer tool

FUD phishing echoes earlier Better Business Bureau-themed attack

May 31, 2007 12:00 PM ET

Computerworld - In the latest narrow-cast attack, security researchers warned today, cybercriminals masquerading as the Internet Revenue Service are counting on the gullibility of business executives.

The e-mail attacks try to dupe recipients into opening the attached file by scaring them with a bogus allegation. "You have received a complaint in regards to your business services," the message begins. "Instructions on how to resolve this complaint as well as a copy of the original complaint are attached to this email."

Other social engineering tricks used by the attackers include the tax agency's logo in the message body, an attached Word document named COMPLAINT.rtf, and the message addressed directly to the recipient.

"Attacks targeting executives are increasingly common," said Ken Dunham, director of VeriSign iDefense's rapid response team, in an e-mail. "This latest attack is not highly prevalent on a global scale but represents a clear and present emergent threat against corporate executives."

If users launch the COMPLAINT.rtf attachment, a phony error message appears and a Trojan horse, called Robofo by Symantec Corp., installs. This backdoor steals passwords from browsers, instant messengers, and other software, then sends it to one of three hacker servers.

IDefense researchers also found a text string embedded in the malware's code -- "MrTheif11" -- that links the Trojan's author to an attack last week disguised as e-mail from the Better Business Bureau (BBB). Like the bogus IRS messages, those from the BBB came with files posing as Word .rtf documents and claimed to be complaints lodged against the recipient.

Targeted attacks against small numbers of corporate users have been on the upswing since early 2006, and although not the case here, often rely on malformed Microsoft Office documents. Microsoft Corp., in fact, has recently released enterprise tools and counseled companies on how to block malicious Word, Excel, and PowerPoint files.

Read more about Security in Computerworld's Security Topic Center.

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