Microsoft was hustling on Tuesday to fix a flaw that left its Windows operating platform vulnerable to attacks from hackers, the company announced.
"It is even worse than a critical flaw," said Rob Helm, director of research at Directions on Microsoft in Washington.
"This one is particularly nasty because is allows people to take control of your computer from over the Internet," he said.
A software "patch" was in the final phases of testing and Microsoft intended to simultaneously release it worldwide in 23 languages on Jan. 10, according to the US-based company.
"Microsoft has been carefully monitoring the attempted exploitation of the Windows Meta File [WMF] vulnerability since it became public last week," the company said in a written release.
"Although the issue is serious and the attacks are being attempted, Microsoft's intelligence sources indicate that the scope of attacks is limited," the statement read.
Microsoft began working on the patch after getting word on Dec. 27 of attacks on Windows operating platform users, the company said.
"There have been real attacks; this is not theoretical," Helm said. "All you have to do is go to an evil Web site or click on a link in an e-mail and some hacker dude owns your computer."
The WMF flaw evidently went undetected and unexploited for several generations of Windows operation platforms, according to analyst Michael Cherry at Directions, a private research firm focused on Microsoft.
The vulnerability allows malicious code to be slipped into an unsuspecting user's computer via graphics files, analysts explained.
"I don't know if panic is the right word, but computer users shouldn't take this lightly," Cherry said. "You need to be protecting your system from all these kinds of outbreaks."
People should have the latest software patches on their computers and be using anti-spy and anti-virus programs updated with the latest "signatures," or threat information.
To minimize the risk of hacker attack, avoid "dodgy" Web sites and don't click on links in e-mails, even those from friends, Helm advised.
"There are risks even with known, major Web sites," Helm explained, "but they are more difficult to exploit."
This new hacker peril for Windows users could inspire computer users to consider switching to different platforms, such as the Macintosh system crafted by Apple Computers in Silicon Valley, Cherry said.
"I think it is a serious problem for Microsoft, because people start looking for alternatives," Cherry said. "Part of the reason Windows is attacked so much is because it is such a large part of the market."
"That doesn't relieve them of the responsibility of defending against it," he said.
Updated anti-virus software has been effective in warding off the hacker attacks, according to Microsoft.