In one implementation, a method for providing security on an externally connected controller includes launching, by the controller, a kernel level security layer that includes a whitelist of permitted processes on the controller, the whitelist being part of a custom security policy for the controller; receiving, at the security layer, a request to run a particular process; determining, by the security layer, a signature for the particular process; identifying, by the security layer, a verified signature for the process from the whitelist; determining, by the security layer, whether the particular process is permitted to be run on the controller based on a comparison of the determined signature with the verified signature from the whitelist; and blocking, by the security layer, the particular process from running on the automotive controller based on the determined signature not matching the verified signature for the process.