Apple does about-face, fixes Safari's 'carpet bomb' bug

Updates the Windows browser to block blended attacks that also involve IE

Apple Inc. updated the Windows version of Safari today, patching four vulnerabilities, including one that prompted rival Microsoft Corp. three weeks ago to urge users to stop using Apple's browser.

The fix stymies the kind of attacks that security researcher Nitesh Dhanjani disclosed last month. Dhanjani dubbed them "carpet bomb" attacks because they could litter the Windows desktop with malware files by taking advantage of a design flaw in Safari.

Today's patch is an about-face of sorts for Apple. The company earlier had told Dhanjani that it didn't consider the problem a security issue because Safari had no option to require a user's permission to download a file. Instead, Apple said it would consider the change an "enhancement request" and perhaps make a modification in a future feature update.

The Stopbadware.org anti-malware group chided Apple for the decision, and asked the Cupertino, Calif., company to reconsider.

It appears that Apple did just that. Safari 3.1.2 now notifies the user before downloading a file, said Apple in the advisory that accompanied today's fixes. "Also," said Apple, "the default download location is changed to the user's Downloads folder on Windows Vista, and to the user's Documents folder on Windows XP."

That last move was in reaction to information released by another researcher, Aviv Raff, also last month. Raff said a vulnerability in Internet Explorer that he had reported in late 2006 would let hackers execute remote code on PCs that also have Safari installed. This "blended threat," Raff added, could allow attackers to hijack vulnerable machines.

Microsoft picked up on Raff's disclosure and issued a security advisory May 30 that recommended users stop using Safari until patches were in place. Among the moves users could make in the meantime, Microsoft said, was to change Safari's default download location.

Microsoft has not yet patched the vulnerability in IE.

Two of the three remaining bugs patched by Safari 3.1.2 were pegged by Apple with the phrase "arbitrary code execution," an indication that the vulnerability is serious and could be used by attackers to compromise computers. Of those flaws, the most dangerous is one that had been reported by a researcher at US-CERT, the public-private clearinghouse that is part of the Department of Homeland Security.

"If a Web site is in an Internet Explorer 7 zone with the 'Launching applications and unsafe files' setting set to 'Enable,' or if a Web site is in the Internet Explorer 6 'Local intranet' or 'Trusted sites' zone, Safari will automatically launch executable files that are downloaded from the site," Apple explained in the advisory. To stop such attacks, Safari no longer automatically launches downloaded executables, and instead prompts the user before downloading a file, assuming the browser's 'Always prompt' setting is turned on.

Other patches fix an information disclosure bug triggered by malicious .bmg or .gif images, and plug a hole in the browser's handling of JavaScript arrays.

Safari for Windows 3.1.2 can be downloaded from Apple's site, while existing installations can be updated using the browser's built-in update feature.

The Mac OS X edition of Safari was not updated today.

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