how to change Out of the Box Icons in CRM 2013

Hi All,

How can I update the Out of the Box icons in CRM 2013. For custom entities I created I can change it easily by clicking the Update Icons Button at the top of the entity. but i wan not able to find the location to change the OOB entities Icons.

• I want to change the icons for Administration, Data Management, Processes  and Solutions. 

any Idea? 

Thanks,