If you're viewing the above screenshot on your site with Chrome, your site has been compromised by the Timthumb vulnerability. The best thing you can do is to follow the instructions provided below.
What can I do?
- To fix the Timthumb vulnerability, download and use the Timthumb Vulnerability Scanner plugin.
- Replace your compromised theme files with a clean copy.
- Upgrade or restore your WordPress installation.
Finally, you have to notify Google that now your site is safe again. Use the Reconsider site functionality provided by Google.