You are allowed if something is not copyrighted howell it's considered "bad" to copy other people their work without giving them credit so if I were you I would either remove it or give Cubecraft credit for building it.
I did find this:
"Copyright, a form of intellectual property law, protects original works of authorship including literary, dramatic, musical, and artistic works, such as poetry, novels, movies, songs, computer software, and architecture."
"Your work is under copyright protection the moment it is created and fixed in a tangible form that it is perceptible either directly or with the aid of a machine or device. "
"In general, registration is voluntary. Copyright exists from the moment the work is created."