McAfee has detected a piece of malware that masquerades as part of the Firefox browser, the security vendor has said.
McAfee calls the Trojan FormSpy. Trojans are programs, often attached to spam email, that appear innocuous but are harmful to a computer.
FormSpy is downloaded to a computer that is already infected with another Trojan called Downloader-AXM, McAfee said. That Trojan was recently detected in email 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 a NumberedLinks 0.9 extension, McAfee said. The extension would normally 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 website, which could include credit card numbers, passwords and electronic banking pin numbers, according to McAfee. FormSpy can also steal email, ICQ instant messaging and FTP (file transfer protocol) passwords, it said.