'Avoid using Microsoft Internet Explorer until bug fixed'

The U.S. and UK governments on Monday advised computer users to consider using alternatives to Microsoft Corp's Internet Explorer browser until the company fixes a security flaw that hackers used to launch attacks.

The Internet Explorer bug, disclosed over the weekend, is the first high-profile computer threat to emerge since Microsoft stopped providing security updates for Windows XP earlier this month. That means PCs running the 13-year-old operating system will remain unprotected, even after Microsoft releases updates to defend against it.

The Department of Homeland Security's U.S. ComputerEmergency Readiness Team said in an advisory released on Mondaythat the vulnerability in versions 6 to 11 of Internet Explorercould lead to "the complete compromise" of an affected system.

The recently established UK National Computer EmergencyResponse Team issued similar advice to British computer users,saying that in addition to considering alternative browsers,they should make sure theirantivirus software is current andregularly updated.

Versions 6 to 11 of Internet Explorer dominate desktop browsing, accounting for 55 percent of global market share, according to research firm NetMarketShare.

(Also see: Microsoft issues a zero-day exploit warning for Internet Explorer versions 6 thru 11)

Boldizsar Bencsath, assistant professor with Hungary'sLaboratory of Cryptography and Systems Security, said the bestsolution was to use another browser such as Google Inc's Chrome or Mozilla's Firefox.

Delayed upgrades
Security experts have long been warning Windows XP users toupgrade to Windows 7 or 8 before Microsoft stopped supporting it at the beginning of this month.

(Also see: Microsoft Windows XP support ends, hackers may be lurking)

The threat that emerged over the weekend could be the wakeupcall that prompts the estimated 15 to 25 percent of PC users whostill use XP to dump those systems.

"Everybody should be moving off of it now. They should havedone it months ago," said Jeff Williams, director of securitystrategy with Dell SecureWorks.

Roger Kay, president of Endpoint Technologies, expectsseveral hundred million people running Windows XP to dump thosemachines for other devices by the end of the year.

They will be looking at Windows machines as well as AppleInc's Macs and iPads along with Google'sChrome laptopsand Android tablets, he said.

"Not everybody will necessarily go to Windows, but Microsofthas a good chance at getting their business," he said. "It's gotto be a good stimulus for the year."

News of the vulnerability surfaced over the weekend.Cybersecurity software maker FireEye Inc warned that asophisticated group of hackers have been exploiting the bug in acampaign dubbed "Operation Clandestine Fox."

© Thomson Reuters 2014