The US and UK governments advised computer users to consider using alternatives to Microsoft's Internet Exploder browser until the company fixes a security flaw that hackers used to launch attacks.
The Department of Homeland Security's U.S. Computer Emergency Readiness Team said in an advisory that the vulnerability in versions 6 to 11 of Internet Explorer could lead to "the complete compromise" of an affected system.
The UK National Computer Emergency Response Team told British computer users, that in addition to considering alternative browsers, they should make sure their antivirus software is current and regularly updated.
Versions 6 to 11 of Internet Explorer dominate desktop browsing, accounting for 55 percent of global market share, according to research firm NetMarketShare so there are lot of people who are going to have to download a different browser.
Cybersecurity software maker FireEye warned that a sophisticated group of hackers have been exploiting the bug in a campaign dubbed "Operation Clandestine Fox".
There is an additional concern that even after Microsoft fixes the bug; it will not be available to those who use Windows XP. Microsoft has stopped upgrading XP except for selected customers who pay for it. There has been a reluctance for some businesses and uses to go off the aging operating system despite government warnings that use of the software might endanger your business' health.