You have absolutely no knowledge of what evidence they have.

Yes I have. The knowledge that no one to date can say with certainty that the Russians did it. If they had that evidence they would say they know who did it. Not that it is very likely.

As to just who doubts it. Well, anyone who says they are certain. Everyone else has doubts. Note, this is not saying the Russians did not do it. Just that there is an element of doubt in the minds of all but a few hardened red under the bed fanatics.