Well, I had it on my now-defunct website without a watermark. It happened to be one of the top images that comes up if you look up Enterprise
cross-sections on Google
(more often than not, the
top one) and the same is true for the watermarked version I have on my DeviantArt account.
So if one plus one equals two, then they must have snagged it off there. Maybe they thought it was official?
I didn't know for a long time until a fellow board member pointed it out to me. (I don't actually own one.) I've never tried to get anything from them, because the way I figure it, it's fan art and I don't own the Enterprise
design. It doesn't seem worth the effort.
I am slightly curious if it still appears on the newer-style boxes, though, if anyone knows.