shadigeb on "New code (?f2bdd7) added to all my website images!"

Hello,

When I look at the status bar or at view image info I notice that this code: ?f2bdd7 is added to the end of my website images URL.
Like this one: http://exemple.com/wp-content/uploads/2016/01/maintaining-a-healthy-body-weight.jpg?f2bdd7

Is this normal or it is a malware ?

I am waiting for your kind reply.
Thanks.