The physical attack surface is the totality of the security vulnerabilities in a given system that are available to an attacker in the same location as the target.
The physical attack surface is exploitable through inside threats such as rogue employees, social engineering ploys and intruders posing as service workers, especially in public companies. External threats include password retrieval from carelessly discarded hardware, passwords on sticky notes and physical break-ins.
Physical access is a very direct attack surface. Many experts consider a data breach inevitable, given enough time, if stored data is not physically secured. An intruder might steal or download the information from an entire drive and extract the target data at a later time, perhaps overcoming encryption with powerful CPUs or general purpose GPU (GPGPU) computing. If the goal is merely to block access or interrupt operations, an attacker may just physically damage equipment – a nearby fire ax would do the trick.
Best practices for reducing the physical attack surface include enforcing secure authentication, zeroing hard drives before throwing out old hardware and refraining from leaving exploitable information – such as sticky note password reminders -- in the physical environment.
Because many attack methods employ a combination of attack surfaces, efforts to protect a resource should analyze the vulnerabilities of all attack surfaces. Attack surface analysis is crucial to proper set up of breach detection systems (BDS), firewall, intrusion prevention systems, data policy and other security measures.
See also: software attack surface, network attack surface, social engineering attack surface