I bought some frames off of Amazon and they included the fasteners. Not too concerned about someone stealing my plates to be honest. Just used what they supplied.I'm familiar with security fasteners. In that case, just use security fasteners to secure the license plates. I have to say that I've bought a lot of license plate frames over the years, but I don't remember any of them coming with security fasteners. If security is your concern, all you need is the fasteners They're readily available. No frame required.
Some frames come with tamper proof screws that require a special tool to install or remove. I have them on my truck. Typically a torx screw with a pin in the middle, tool has a hole in the center for the pin to slide into and the rest is a typical torx screw.