Third party extensions are what make Joomla so wildly popular but these same extensions are what many times lead to an attack on your site. Every extension is another item that you have to ensure is updated / patched. This is the reason it's important to install only the extensions you need. You should be sure to take the following steps:

-- Do a code review on any extension you use

-- Run a test suite (there are many out there) and review your results

-- Update or patch your code as necessary