Not a Viper, just a grey rat snake, incredible climber. Probably wants to speak to you about your cars extended warranty, and eat any rodents you may have.
I don't know if it's fake or not, but it has the pointed snout of a venomous snake. Non-venomous snakes have a more rounded nose. Easy way to tell without knowing what kind of snake it is exactly.
Pic isn't sharp enough to confirm other venomous snake characteristics - scale plates on the head/tail, slit pupils, pits, venom sacks... I'm goin' with Mechdziner's assessment...the skin pattern is near spot on.