Reader X on Windows features Protected Mode, a technology that isolates system processes, preventing or at least hindering malware from escaping the application to wreak havoc on the computer.

The new version is also available for Mac OS X and Android, but those editions lack the sandbox.

Protected Mode is Adobe's response to experts' demands that the company beef up the security of Reader, which is by attackers. Those hackers frequently exploit unknown and unpatched vulnerabilities, called "zero-days," to infect PCs with malware using rigged PDF documents.

Calling the sandbox a "new advancement" in protective measures, Brad Arkin, Adobe's director of and privacy, admitted it will not stymie every attack. But he argued it will help.

"Even if exploitable security vulnerabilities are found by an attacker, Adobe Reader Protected Mode will help prevent the attacker from writing files or installing malware on potential victims' computers," in a post to a company blog late on Thursday.