A month-old flaw in Microsoft Word has opened up PCs to attack by a new Trojan horse, antivirus researchers said Thursday. Dubbed "Goga," the malicious code poses as a Word document saved in rich text format but actually reaches through the Net to run a Word macro--a small program that runs within the application--saved on a Russian Web site. "While this is not a danger to the general public, it could be a danger to somebody if there is a direct mailing to them," said Jimmy Kuo, a researcher at security software maker Network Associates. The Trojan horse appears as text file in the rich text format, or RTF, attached to an e-mail, according to British antivirus software company Kaspersky Labs, which first found the malicious program. When opened, the RTF file will link back to a Word template file on a Russian Web site. The file contains a macro, which will steal and upload information regarding the victim's log-in and password to the guest book of a second site. An investigation of that site found only one record of any information, indicating the Trojan horse is not widespread.