First IE7 Security Flaw Found

Less than 24 hours after the launch of Internet Explorer 7, security researchers are poking holes in the new browser.

Danish security company Secunia reported today that IE7 contains an information disclosure vulnerability, the same one it reported in IE6 in April. The vulnerability affects the final version of IE7 running on Windows XP with Service Pack 2.

If a surfer uses IE7 to visit a maliciously crafted Web site, that site could exploit the security flaw to read information from a separate, secure site to which the surfer is logged in. That could enable an attacker to read banking details, or messages from a Web-mail account, said Thomas Kristensen, Secunia's chief technology officer.

"A phishing attack would be a good place to exploit this," he said.

One of the security features Microsoft touts for the new browser is the protection it offers users from phishing attacks.

Flaw Not Easy to Exploit

Secunia rates the security flaw as "less critical," its second-lowest rating, and suggests disabling active scripting support to protect the computer. The flaw could result in the exposure of sensitive information and can be exploited by a remote system, Secunia said in a security advisory posted on its Web site.

It is hard to exploit the flaw because it requires the attacker to lure someone to a malicious site, and for the attacker to know what other secure site the visitor might simultaneously have open, Kristensen said.

"A quick user browsing through our Web site using IE7 found it failed one of our tests," he said.

The company then verified the information, notified Microsoft and published a proof-of-concept exploit on its Web site.

Update: Microsoft said Oct. 19 that the problem was not with IE 7, but with Outlook Express.