Adobe has issued emergency updates for Adobe Flash Player to fix flaws that are being actively exploited by attackers. The vulnerabilities affect versions of Flash Player running on Windows, Mac OS X, Linux and Android.

The two bugs (CVE-2013-0633 and CVE-2013-0634) allow attackers to run arbitrary code on a targeted system and compromise that system. "Failed exploit attempts will likely result in denial-of-service conditions," read an overview of the attacks published by Symantec.

The first vulnerability, which targets the ActiveX version of Flash Player for Windows, "is being exploited in the wild in targeted attacks designed to trick the user into opening a Microsoft Word document delivered as an email attachment which contains malicious Flash (SWF) content," according to a security warning published by Adobe.

The second vulnerability, meanwhile, is being used in drive-by attacks from websites that target browsers with malicious Flash content. To date, the attacks have targeted OS X versions of Flash Player running Firefox and Safari on the Mac OS X platform. Attackers are also using the vulnerability to target Windows users via Microsoft Word documents -- attached to emails -- that include malicious Flash content.

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Vulnerable software includes Flash Player 11.5.502.146 (and earlier) for both Windows and Mac OS X, Flash Player 11.2.202.261 (and earlier) for Linux, Flash Player 11.1.115.36 (and earlier) for Android 4.x, and Flash Player 11.1.111.31 (and earlier) for Android 3.x and 2.x. Flash users can visit the About Flash Player page on Adobe's website to review which version of Flash they're running. "If you use multiple browsers, perform the check for each browser you have installed on your system," Adobe advised. Flash updates, meanwhile, can be obtained from the Adobe Flash Player download page.

Information security firm FireEye said it first witnessed the in-the-wild attacks that are exploiting the two vulnerabilities on Tuesday. The Word files contain a macro to load an embedded SWF flash object, according to an overview of the attacks published by FireEye. The SWF file contains an action script with the name 'LadyBoyle' that contains the exploit code.

Interestingly, the code and documents used in the attacks were respectively compiled and created Tuesday, and while the contents of the documents are written in English, the files' code pages are set to Windows Simplified Chinese (PRC, Singapore).

Despite attackers actively targeting two new zero-day vulnerabilities in Flash Player, Adobe said that it's been putting changes in place that make it more difficult for attackers to exploit newly discovered Flash bugs. Those changes have included sandboxing, working with browser makers and operating system developers to deliver Flash updates -- and disable older versions of Flash -- and hardening applications that are used to disguise Flash attacks.

"Over the last year, Adobe has been driving down the number of Flash-based zero-days used in the wild," said Peleus Uhley, a senior security researcher within the Secure Software Engineering team at Adobe, in a blog post. "Since the introduction of Adobe Reader X Protected Mode (aka sandboxing) in November 2010, the most common Flash Player zero-day attack vector has been malicious Flash content embedded in Microsoft Office documents and delivered via email."

To address that threat, Microsoft created a Protected Mode sandbox in Microsoft Office 2010 that prevents Flash content in Office documents from executing automatically, if the document originated in either an Internet or Untrusted Zone. But no such safeguards exist in Office 2008, so if a user opens a malicious document any Flash content included in the document will execute automatically.

New features built into the next major release of Flash, which is currently being beta tested, should make it more difficult to attack systems running Microsoft Office 2008 or earlier. "The upcoming release of Flash Player will determine whether Flash Player is being launched within Microsoft Office and check the version of Office," said Uhley. "If Flash Player is launched within a version prior to Office 2010, Flash Player will prompt the end user before executing the Flash content, [displaying a warning that recommends that the content not be allowed to play]."

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