One thing a person can do to protect themselves is to be ready for a confrontation with the backstabber. Many times someone gets away with this behavior because it can work for that person to get ahead. Backstabbers generally count on you not wanting to get in a confrontation so if you confront them they may back down and leave you alone. It would be beneficial to document any communication so you can defend yourself if the need arises.
I personally believe that backstabbing and manipulating is never an okay thing to do. This type of work environment can destroy