Researchers are warning users of Mozilla's Firefox 2.0 on Windows computers that they are vulnerable to attacks exploiting the animated cursor (.ani) bug.Alexander Sotirov, a researcher for the security company Determina who discovered the vulnerability, posted a demonstration online of an .ani exploit that hijacks a Windows machine using the Firefox web browser.
There is no flaw in the Firefox source code itself, but an attacker could exploit the Windows vulnerability using the application programming interface (API) feature in Firefox, Sotirov said.
Hackers are already known to be exploiting the .ani vulnerability, which was made public by Microsoft last week, but only on computers using Internet Explorer. Microsoft released an out-of-cycle patch on Tuesday to tackle the flaw.
“The reason for the confusion over Firefox is that an exploit that works against it has not become public,” said Sotirov. “So in a sense, since there are no attacks in the wild, it is safer. But people should also consider that the bad guys will figure out how to exploit Firefox.”
Sotirov advises users to refrain from using Windows API until they have installed the MS07-017 patch.
Mozilla could not be immediately reached for comment.