correct, it's an augmented 7th, so theoretically , if analyzing harmoney you would follow std conventions and likely derive an altered harmony. it is enharmonic to an octave. it would be a strange chord , not likely encountered out side of very late (and funky modulation or borrowed harmony) romantic or more at home in 20th century and later writing.
so if a 3rd were in there somewhere , you'd be working w/ an ugly 7th chord that would likely have the B# moving to a B natural, it acting as supposed to, however the sharp could lead to a B double sharp or a C natural to c sharp as well depending on the context.