The governments of both countries recommended computer users to switch to alternative web browsers from Internet Explorer, until Microsoft fixes a security flaw used by the attackers to hack into victims’ computers.

According to the U.S. Computer Emergency Readiness Team, which is a unit within the Department of Homeland Security, the vulnerability in versions 6 to 11 of Microsoft’s Internet Explorer could cause “the complete compromise” of an affected system.

In a recently issued advisory, the UK National Computer Emergency Response Team told the UK users that besides considering alternative web browsers, they are better to also make sure their antivirus software is current and regularly updated. As it became recently known, versions 6 to 11 of IE are vulnerable, but they dominate desktop browsing, with more than a half of the world market using it. As a result, now there are a lot of people who want to download a different web browser. The options include Google’s Chrome or Mozilla’s Firefox. By the way, the last time that there was this sort of panic, Mozilla cleaned up, especially in the European Union.

A few days ago, cybersecurity software maker FireEye revealed that a sophisticated group of hackers has been found to be exploiting the bug in a campaign known as “Operation Clandestine Fox”.

Another concern expressed by the industry experts is that even after the software giant fixes the vulnerability; it won’t be available to people who are still using expired Windows XP. Microsoft has stopped supporting XP except for selected customers who pay for it. The market sees a reluctance of many businesses and users to switch from the aging OS even despite the warnings that its use might endanger their business’ health.