The company, GreyMagic Software, detailed what it said are nine new security vulnerabilities in Internet Explorer 5.5 and 6.0. Prior versions aren't vulnerable, and only two of the vulnerabilities affect Internet Explorer 6 if it has Service Pack 1 included, according to GreyMagic in a security posted on its Web site.

With all the vulnerabilities combined, an attacker can "easily steal private local documents, forge trusted Web sites, steal clipboard information, and even execute arbitrary programs," GreyMagic said in a statement sent via e-mail. An attacker would have to lure a user to a specially coded Web site to carry out an attack.

"It would be extremely simple to exploit these new vulnerabilities," said Lee Dagon, security services coordinator at GreyMagic, in an e-mail. "The code used to exploit a client is very short and straightforward, and exploitation is as easy as getting someone to go to a specific Web page."

Users can check which version of Explorer is installed by clicking "About Internet Explorer" in the Help pull-down menu of the browser.

GreyMagic, in Jerusalem, informed Microsoft at the same time that it disclosed details of the vulnerabilities to the public. The company said that in the past "notifying Microsoft ahead of time and waiting for them to patch the reported issues proved nonproductive."

Microsoft said it is concerned by the way GreyMagic reported the vulnerabilities. "Publishing this report may put computer users at risk -- or at the very least could cause needless confusion and apprehension," Microsoft said in a statement.

"Responsible security researchers" work with the maker of the product that is suspected to be vulnerable to "ensure that countermeasures are developed before the issue is made public and customers are needlessly put at risk," the software maker said.

GreyMagic hasn't heard from Microsoft since it reported the vulnerabilities yesterday, said Dagon.

"We end up reading about their reactions in various news items," he said. "Our primary goal in releasing these advisories is to alert users to the risks they are exposed to and suggest workarounds for them to employ. The way we see it, that is the responsible thing to do."

Microsoft didn't confirm the existence of the vulnerabilities but said it is investigating the issues reported by GreyMagic just as it investigates all reports of security flaws in its products.