title: Can Viruses be uploaded to server using upload forms and what can be the impact?
body: <p>I'm implementing an upload form so that my users can upload a background image to my website.</p>
  
  <p>I've never really thought about it before, but I presume that a virus could be uploaded in an image format using my form.</p>
  
  <p>Is it possible and is it likely to bring my website down or leave my users' data vulnerable?</p>
  
  <ul>
  <li>Can people upload dangerous viruses (I'm limiting the upload to jpg, png, bmp 800kb)</li>
  <li>What can I do to protect myself?</li>
  <li>Do most hosts have anti-virus built-in?</li>
  <li>What steps should I take with my code or server to prevent such an event, if anything?</li>
  <li>If a user uploads a virus file to my server and it is shown as the background, could this cause implications for people using the site, or wouldn't it get this far?</li>
  </ul>
  
  <p>I'm using PHP and a Linux Server</p>