Suspicious mesage appears instead of images

My installation is of Multisite setup . when I upload an image and try to view it, getting a message ‘go home baby!!’ instead of image

Actually the specific sub-site is also mapped with a custom domain. I thought that it is breaking the link. So removed the mapped domain and still having the same issue

Tried uploading multiple images and almost every image gives the message. Is that kind of some fraudulent activity or my files were hacked? I don’t think so . I have checked the installation files and nothing suspicious found

Could any one help me with this?