In a rare move that highlights the severity of the security hole in one of the Web’s most popular browsers, the US Computer Emergency Readiness Team and its British counterpart tell people to stop using Internet Explorer until Microsoft can fix it.
It’s not often that the US or UK governments weigh in on the browser wars, but a new Internet Explorer vulnerability that affects all major versions of the browser from the past decade has forced it to raise an alarm: Stop using IE.
The zero-day exploit, the term given to a previously unknown, unpatched flaw, allows attackers to install malware on your computer without your permission. That malware could be used to steal personal data, track online behavior, or gain control of the computer. Security firm FireEye, which discovered the bug, said that the flaw is being used with a known Flash-based exploit technique to attack financial and defense organizations in the US via Internet Explorer 9, 10, and 11. Those versions of the browser run on Microsoft’s Windows Vista, Windows 7, and Windows 8, although the exploit is present in Internet Explorer 6 and above.
While the Computer Emergency Readiness Team in England and the US regularly issue browser advisories, this is one of the few times that the CERT team has recommended that people avoid using a specific browser.
FireEye recommends that if you can’t switch browsers, then you disable Internet Explorer’s Flash plug-in. You also can use IE with Microsoft’s Enhanced Mitigation Experience Toolkit security app, but that will not be as secure as simply switching browsers.
Microsoft and the Department of Homeland Security did not immediately respond to requests for comment.
Statistics vary as to how many people actually use Internet Explorer. NetMarketShare puts the total around 55 percent of the desktop browser market, while competitor StatCounter says that 22.58 percent of people use IE. While the disparity is large, in either case the flaw affects a huge number of browsers being actively used.
Updated, 4:13 p.m. PT: to add UK CERT position on Internet Explorer.