Trojan cloaks itself as Firefox extension

Security vendor McAfee has detected a new piece of malicious software that masquerades as part of the Firefox Internet browser.

McAfee calls the Trojan horse "FormSpy." Trojan horses are programs, often attached to spam e-mail, that appear innocuous but are harmful to a computer.

FormSpy is downloaded to a computer that is already infected with another Trojan horse called "Downloader-AXM," McAfee said. That Trojan was recently detected in e-mail spam messages.

Downloader-AXM contacts servers to download other malicious programs to a computer without a user's knowledge, according to McAfee. Once downloaded, FormSpy installs itself as a Firefox extension.

The program appears as "NumberedLinks 0.9" extension, McAfee said. The extension normally would allow a user to navigate links by numbers using the keyboard rather than a mouse.

Then, FormSpy can transmit information in a Web browser to another Web site, which could include credit card numbers, passwords and electronic banking pin numbers, according to McAfee. FormSpy can also steal e-mail, ICQ instant messaging service and FTP passwords, it said.

The IDG News Service is a Network World affiliate.