Updated Security researchers from Symantec have clarified an earlier report of attack code in the wild that targets a previously unknown vulnerability in the latest version of Adobe Flash. They now say current versions of Adobe's stand-alone Flash application are vulnerable, but that updated browser plug-ins are not.

At least 20,000 web pages have been found to carry links to a site that hosts malicious Flash applets that exploit the weakness, according to Symantec. While Flash plug-ins for Internet Explorer, Firefox and other browsers are immune to the attack, Adobe's stand-alone application for Flash is vulnerable, said Ben Greenbaum, a senior research manager at Symantec Security Response.

The security bug is a variation of one that Adobe has recently patched, but evidently, the update didn't work as expected. "This was one of the vulnerabilities that was reported as having been fixed," he said. "In the stand-alone versions, it does not happen."

The clarification is good news because the number of people using the application is relatively small. The Flash plug-in, by contrast, is installed on just about every computer known to man, thanks to its availability on Windows, Mac and Linux platforms and the huge number of sites that require their visitors to use it. A well-executed attack of a zero-day flaw in the ubiquitous program could prove critical.

The malicious links are likely to be the result of SQL injections, an attack method that's grown rampant in recent weeks. The links silently redirect end users to a site that preys on a vulnerability in Flash Player versions 9.0.124.0 and older, according to this advisory from the Sans Internet Storm Center.

The seriousness of the vulnerability and the extent of the attack are still unclear. According to Symantec, "an attacker may exploit this issue to execute arbitrary code in the context of the affected application. Failed exploit attempts will likely result in denial-of-service conditions." Researchers at Symantec and Adobe were still analyzing the attack on Wednesday morning, Greenbaum said.

In a separate advisory, Sans is reporting the hosting of malicious SWF files, but it's unclear if they are related to the recently discovered vulnerability or to one that has already been patched.

Adobe says it's investigating the Symantec report. ®

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