Adobe’s PDF document format is pretty popular. I am willing to bet most people have Adobe PDF Reader software installed on their PC.
The trouble with software is the more popular it is the more attractive it is to hackers etc to try and exploit it for malicious gain – can you say Windows! So with Adobe Reader being so common whenever a security flaw is found it is highly likely that there are some internet baddies out there trying to take advantage of it.
Adobe are pretty vigilant about upgrading the product regularly to address any flaws and this is the case now. The only downside is that the program is a pretty big download each time.
To keep yourself safe make sure you upgrade to Version 9 (or at least 8.1.3 or higher)
Alternatively I quite like Foxit PDF Reader. It performs the same functions for most users, includes some unique features that the free Adobe program doesn’t like adding bookmarks. Best of all it is free and a much smaller download. Check out the features in the review linked below. If you do install be sure to say ‘No’ to installing the Yahoo toolbar and eBay icon (unless you really want them)