Unless the media has a Creative Commons "No Rights Reserved" license you must attribute what you use.
Creative Commons allows creators to provide their work with different licenses, which in turns allows people to use the content with proper recognition. With some license options you can reuse, remix, and/or repurpose other's content.
Photo credit: SUNY OER Services.
To properly attribute ownership to a work it should include:
All items should be linked to source. Use as many elements are you can. If for example, you don't have the name of the work use something like photo. See CC wiki for best practices.