Adobe Patches Zero-Day XSS Vulnerability in Flash Player 10

Adobe launched an emergency out-of-band update for its Flash Player 10 on the same day it announced the latest version of its Web multimedia platform, Flash 11.

A week after the quarterly patch update for Adobe Acrobat and Reader, Adobe released an emergency update to address a zero-day vulnerability in its Flash Player.

Adobe announced the out-of-cycle patch on Sept. 21 to fix a zero-day vulnerability and several critical issues affecting Flash Player 10 and earlier versions for Windows, Macintosh, Android, Linux and Solaris. One of the bugs, rated "important," is a universal cross-site scripting issue that can be used by remote attackers to perform Website actions on a Web page or Webmail account on the user's behalf, Adobe said in its security advisory.

"I think we can interpret this to mean that a successful attack using this zero-day bug could allow the attacker to access the user's Gmail account," Andrew Storms, director of security for nCircle, told eWEEK. A malicious campaign earlier this year took advantage of a different zero-day in Flash that allowed perpetrators to impersonate a user on various sites, including Google's Gmail and on financial Websites. Adobe patched that cross-site scripting flaw on June 5 after Google reported the issue.

The latest Flash Player update fixed six vulnerabilities. The critical vulnerabilities could cause a crash and potentially allow an attacker to take control of the affected system when a user visits a Web page seeded with malicious Flash files, Adobe said. The issues in the Flash update have already been addressed for Adobe Reader and Acrobat in last week's quarterly patch update, Adobe said.

"There are reports that one of these vulnerabilities is being exploited in the wild in active targeted attacks designed to trick the user into clicking on a malicious link delivered in an e-mail message," Adobe warned. It appears that Google reported this cross-site vulnerability as well.

The vulnerability is "not straight forward to exploit," Chester Wisniewski, a senior security adviser at Sophos, wrote on the Naked Security blog.

"It’s time for all IT teams to circle the wagons and patch Flash as soon as possible," Storms said.

Google patched the version of Adobe Flash that is integrated in its Chrome for Windows Web browser a day earlier, on Sept. 20. Google generally releases Chrome updates to fix Flash issues before Adobe. Adobe develops the patch, but since there are only a handful of configurations to test against Chrome, those updates are ready sooner and pushed to Google while Adobe finishes testing other browser and operating system combinations, according to Wiebke Lips, Adobe’s senior manager of corporate communications.

Since the exploit is already in the wild, Google releasing the patch before Adobe doesn't really make much of a difference. "It's probably easier for attackers to get the exploit code directly instead of trying to decipher it from Adobe's patch or even Chrome's code changes," Storms said.

The patch was released on the same day that Adobe is touting the new 3D graphics capabilities in Flash 11, which will be available in early October.

"Serious stuff, and every Internet user (well, those who use Flash—so owners of iPhones and iPads can relax) would be wise to ensure that they update their computers as soon as possible once the patch is released," Graham Cluley, senior technology consultant at Sophos, added on the Naked Security blog.

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