Foxit patches critical flaw in PDF viewer browser plug-in

Vulnerability has been publicly known for a over a week

Foxit released version 5.4.5 of its Foxit Reader PDF viewer plug-in on Thursday in order to address a critical remote code execution vulnerability that could have allowed attackers to compromise computers running previous versions of the software.

The vulnerability was located in the Foxit Reader browser plug-in for Mozilla Firefox, Google Chrome, Opera and Safari and could have been exploited by tricking users into opening an URL to a PDF document with an extremely long file name. The plug-in -- npFoxitReaderPlugin.dll -- is installed by default unless users clear a checkbox during the Foxit Reader installation process.

Foxit Reader 5.4.5 contains a patched version of the browser plug-in, Foxit said in an advisory published on its website. Users are advised to upgrade to the newly released version by using the "Check for Updates Now" link under the application's "Help" menu.

In its advisory, Foxit credits vulnerability research firm Secunia with discovering the flaw. However the vulnerability was actually found by independent security researcher Andrea Micalizzi.

Micalizzi publicly disclosed details about the vulnerability and how it can be exploited on his website on Jan. 7, meaning that it had zero-day -- publicly known, but unpatched -- status at the time. Secunia credited Micalizzi in its own advisory on Jan. 8.

Foxit Reader has often been advanced in the past as a safer alternative to Adobe Reader. Foxit advertises the application as "the most secure PDF reader" on its website and claims that it has over 130 million users.

PDF exploits are not as commonly used in Web-based attacks today as they were a few years ago. However, many Web exploit toolkits used by cybercriminals still contain such exploits, the vast majority of which target vulnerabilities in outdated versions of Adobe Reader.

Newer versions of Adobe Reader like Adobe Reader X (10) and XI (11) have a sandboxing mechanism that makes the exploitation of remote code execution vulnerabilities very hard.

Some browser vendors are also trying to make it harder for attackers to use PDF exploits. Mozilla recently added a built-in, and allegedly more secure, PDF viewer to the beta version of Firefox and expects it to become a stable feature in the next version of the browser, Firefox 19.

Google Chrome has had a built-in PDF viewer since 2010. The component is actually built using Foxit's PDF SDK (software development kit), but is protected by the browser's native sandbox.

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