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Physical security is the protection of corporate assets from threats such as theft or damage. There are three factors to keep in mind with physical security:

  • Prevention is making the location less tempting to break into.
  • Detection is identifying what was broken into, what is missing, and the extent of the damage.
  • Recovery is the review of the physical security procedures, fixing any damage, and hardening the physical security of the company against future problems.

Important aspects of physical security are:

  • Restricting physical access to facilities and computer systems
  • Preventing interruptions of computer services caused by problems such as loss of power or fire
  • Preventing unauthorized disclosure of information
  • Disposing of sensitive material
  • Protecting the interior and exterior of your facility

The table below lists physical control measures and their characteristics:

Control Measure Characteristics
Perimeter barriers For a secure facility, the first physical security measure is to secure the building perimeter and restrict access to only secure entry points. Methods for securing the perimeter include:
  • Fences provide an environmental barrier that prevents easy access to the facility.
    • A low fence (3 to 4 feet) acts as a deterrent to casual intrusion.
    • A higher fence (6 to 7 feet) acts as a deterrent unless the trespasser has a specific intent to violate security.
    • A fence 8 feet or higher topped with barbed wire is an effective deterrent.
  • Guard dogs are generally highly reliable but appropriate only for physical perimeter security. They can be expensive to keep and maintain, and their use might raise issues of liability and insurance.
  • Lighting deters casual intruders, helps guards see intruders, and is necessary for most cameras to monitor the area. To be effective, lights should be placed to eliminate shadows or dark spots.
  • Security guards offer the best protection for perimeter security because they can actively respond to a variety of threat situations. However, guards are expensive, require training, and can be unreliable or inconsistent. Security guards can also reference an access list which explicitly lists who can enter a secure facility.
Closed-circuit television (CCTV) Closed-circuit television can be used as both a preventative tool (when monitoring live events) or as an investigative tool (when events are recorded for later playback). Camera types include:
  • A bullet camera has a built-in lens and is long and round in shape. Most bullet cameras can be used indoor or outdoor.
  • A c-mount camera has interchangeable lenses and is typically rectangle in shape with the lens on the end. Most c-mount cameras require a special housing to be used outdoors.
  • A dome camera is a camera protected with a plastic or glass dome. These cameras are more vandal-resistant than other cameras.
  • A Pan Tilt Zoom (PTZ) camera lets you dynamically move the camera and zoom in on specific areas to monitor (cameras without PTZ capabilities are manually set looking a specific direction). Automatic PTZ mode automatically moves the camera between several preset locations; manual PTZ lets an operator remotely control the position of the camera.
When selecting cameras, be aware of the following characteristics:
  • The focal length measures the magnification power of a lens. The focal length controls the distance that the camera can see, as well as how much detail can be seen at a specific range.
    • The focal length is expressed in millimeters (mm). A higher focal length lets you see more detail at a greater distance.
    • Most cameras have a 4mm lens with a range of 30-35 feet, allowing you to see facial features at that distance.
    • A fixed lens camera has a set focal length. A varifocal camera lens lets you adjust the focus (zoom).
  • A lens with a 70 degree angle of view is the largest view angle possible without distorting the image.
  • The resolution is rated in the number of lines (such as 400) included in the image. In general, the higher the resolution, the sharper the image.
  • LUX is a measure of the sensitivity to light. The lower the number, the less light needed for a clear image.
  • Infrared cameras can record images in little or no light. Infrared cameras have a range of about 25 feet in no light, or further in dimly-lit areas.
When used in a preventative way, you must have a guard or other person available who monitors one or more cameras. Cameras themselves can detect security breaches, but guards can prevent and react to security breaches.
Doors Doors can enhance security if they are properly implemented. Specific door types include:
  • A mantrap is a specialized entrance with two doors that creates a security buffer zone between two areas.
    • Once a person enters into the space between the doors, both doors are locked.
    • To enter the facility, authentication must be provided. This may include visual identification and identification credentials.
    • Mantraps should permit only a single person to enter, and authentication must be provided by each person.
    • If authentication is not provided, the intruder is kept in the mantrap until authorities arrive.
  • A turnstile is a barrier that permits entry in only one direction.
    • Physical turnstiles are often used to control entry for large events such as concerts or sporting events.
    • Optical turnstiles use sensors and alarms to control entry.
    • Turnstiles are often used to permit easy exit from a secure area. Entry is controlled through a mantrap or other system that requires authentication for entry.
  • A double entry door has two doors that are locked from the outside but with crash bars on the inside that allow easy exit. Double entry doors are typically used only for emergency exits, and alarms sound when the doors are opened.
Regular doors are susceptible to social engineering attacks such as piggybacking (tailgating) where an unauthorized person will ask an authorized person to "hold the door." Mantraps and turnstiles that permit only a single person and require individual authentication are effective deterrents to piggybacking.
Door locks Door locks allow access only to those with the proper key. Lock types include:
  • Pick resistant locks, with restricted key duplication, are the most secure key lock. It is important to note that all traditional key locks are vulnerable to lock-picking (shimming).
  • Keypad locks require knowledge of a code and reduce the threat from lost keys and cards. Clean keypads frequently to remove indications of buttons used.
  • Electronic systems often use key cards(or ID badges) instead of keys to allow access.
    • Dumb cards contain limited information.
    • Smart cards have the ability to encrypt access information. Smart cards can be contact or contactless. Contactless smart cards use the 13.56 MHz frequency to communicate with proximity readers.
    • Proximity cards, also known as RFID (radio frequency identification) cards, are a subset of smart cards that use the 125 kHz frequency to communicate with proximity readers. Proximity cards differ from smart cards because they are designed to only communicate the card's ID; whereas, the smart card can communicate much more information.
  • Biometric locks increase security by using fingerprints or iris scans. They reduce the threat from lost keys or cards.
Physical access logs Physical access logs are implemented by guards of a facility and require everyone gaining access to the facility to sign in.  
Physical access controls Physical access controls can be implemented inside the facility.
  • Physical controls may include key fobs, swipe cards, or badges.
  • To control access to sensitive areas within the facility, require a card swipe or reader.
  • Some systems can track personnel movement within a facility and proactively lock or unlock doors based on the access token device.
  • An anti-passback system prevents a card holder from passing their card back to someone else.
  • Physical controls are often implemented together with sensors and alarms to detect unauthorized access.
    • Photoelectric sensors detect motion and are best suited to detect a perimeter breach rather than interior motion detection.
    • Wave pattern, heat sensing, and ultrasonic sensors are all better suited for interior motion detection than perimeter breach detection.

Physical security should deploy in the following sequence. If a step in the sequence fails, the next step should implement itself automatically.

  1. Deter initial access attempts.
  2. Deny direct physical access.
  3. Detect the intrusion.
  4. Delay the violator to allow for response.

When designing physical security, implement a layered defense system. A layered defense system is one in which controls are implemented at each layer to ensure that defeating one level of security does not allow an attacker subsequent access. Using multiple types of security controls within the same layer further enhances security. Tips for implementing a multi-layered defense system are:

  • Protect entry points with a card access system (or some other type of control) as well as a security camera.
  • Use a reception area to prevent the public, visitors, or contractors from entering secure areas of the building without an escort.
  • Use the card access or other system to block access to elevators and stairwells. This will prevent someone who successfully tailgates from gaining further access.
  • Use a different access system to secure offices or other sensitive area such as key locks, keypad locks, or biometric controls.
  • Implement security within offices and data centers using locking storage areas and computer passwords.

Perform physical security inspections quarterly. Violations should be addressed in a formal manner with warnings and penalties imposed.