(My) CISSP Notes – Physical Security

Note: This notes were made using the following books: “CISPP Study Guide” and “CISSP for dummies”.

Physical (Environmental) security protects the Confidentiality, Integrity and Availability  of physical assets: people, buildings, systems, and data. The CISSP® exam considers human safety as the most critical concern of this domain, which trumps all other concerns.

Physical security protects against threats such as unauthorized access and disasters, both man-made and natural. Controls used in this domain are primarily physical (such as locks, fences, guards, etc.); administrative controls (such as policy and procedures) and technical (such as biometrics) are also used.

Physical access control

Physical access control consists of the systems and techniques used to restrict access to a security perimeter and provide boundary protection.

Types of Vehicle Gates :

  • class 1 – residential (home use)
  • class 2 – commercial/general access (parking garage)
  • class 3 – industrial/limited access
  • class 4 – restricted access

A traffic bollard is a strong post designed to stop a car.

Lock picking is the art of opening a lock without a key.

The master key opens any lock for a given security zone in a building.

The core key is used to remove the lock core in interchangeable core locks (where the lock core may be easily removed and replaced with another core).

A smart card is physical access control device which is often used for electronic locks, credit card purchases, or dual-factor authentication systems.

A magnetic stripe card contains a magnetic stripe which stores information.

A mantrap is a preventive physical control with two doors. The first door must close and lock before the second door may be opened. Each door typically requires a separate form of authentication to open.

Turnstiles are designed to prevent tailgating by enforcing a “one person per authentication” rule, just as they do in subway systems.

Technical controls

Technical control include monitoring and surveillance, intrusion detection systems and alarms.

Closed Circuit Television (CCTV) is a detective device used to aid guards in detecting the presence of intruders in restricted areas.Key issues include depth of field (the area that is in focus) and field of view (the entire area viewed by the camera). More light allows a larger depth of field because a smaller aperture places more of the image in focus. CCTV displays may display a fixed camera view, autoscan (show a given camera for a few seconds before moving to the next), or multiplexing (where multiple camera feeds are fed into one display).

Ultrasonic, microwave, and infrared motion sensors are active sensors, which means they actively send energy.

If you see the term “intrusion” on the exam, be sure to look for the context (human or network-based).

Door hinges should face inward, or be otherwise protected. Externally-facing hinges that are not secured pose a security risk: attackers can remove the hinge pins with a hammer and screwdriver, allowing the door to be opened from the hinge side.

Use of simple glass windows in a secure perimeter requires a compensating control such as window burglar alarms.

Environmental and life safety controls

Environmental controls are designed to provide a safe environment for personnel and equipment. Power, HVAC, and fire safety are considered environmental controls.

The following are common types of electrical faults:

  •  Blackout: prolonged loss of power
  • Brownout: prolonged low voltage
  • Fault: short loss of power
  • Surge: prolonged high voltage
  • Spike: temporary high voltage
  • Sag: temporary low

Heat detectors, flame detectors, and smoke detectors provide three methods for detecting fire.

The two primary evacuation roles are safety warden and meeting point leader.

Classes of Fire and Suppression Agents :

  • Class A  – fires are common combustibles such as wood, paper, etc. This type of fire is the most common and should be extinguished with water or soda acid.
  • Class B  – fires are burning alcohol, oil, and other petroleum products such as gasoline. They are extinguished with gas or soda acid. You should never use water to extinguish a class B fire.
  • Class C  – fires are electrical fires which are fed by electricity and may occur in equipment or wiring. Electrical fires are Conductive fires, and the extinguishing agent must be non-Conductive, such as any type of gas.
  • Class D  – fires are burning metals and are extinguished with dry powder.
  • Class K – fires are kitchen fires, such as burning oil or grease. Wet chemicals are used to extinguish class K fires.

Experts always prefer to prevent a fire rather than extinguish one, and are often generous with their time dedicated to preventive measures.

All fire suppression agents work via four methods (sometimes in combination): reducing the temperature of the fire, reducing the supply of oxygen, reducing the supply of fuel, and interfering with the chemical reaction within fire.

Always consider “hire or ask an expert” as a valid choice for any exam question asking about “the best thing to do.” Do not fall for the engineer’s trap of “I will figure this out on my own.”

Water suppresses fire by lowering the temperature below the kindling point (also called the ignition point). Water is the safest of all suppressive agents, and recommended for extinguishing common combustible fires such as burning paper or wood.

In addition to suppressing fire by lowering temperature, soda acid also has additional suppressive properties beyond plain water: it creates foam which can float on the surface of some liquid fires, starving the oxygen supply.

Extinguishing a fire with dry powder (such as sodium chloride) works by lowering temperature and smothering the fire, starving it of oxygen. Dry powder is primarily used to extinguish metal fires.

Wet chemicals are primarily used to extinguish kitchen fires (type K fires in the U.S.; type F in Europe), but may also be used on common combustible fires (type A).

CO2, oxygen, and nitrogen are what we breathe as air. Fires require oxygen as fuel, so fires may be smothered by removing the oxygen: this is how CO2 fire suppression works. A risk associated with CO2 is it is odorless and colorless, and our bodies will breathe it as air. By the time we begin suffocating due to lack of oxygen, it is often too late.

Halon extinguishes fire via a chemical reaction that consumes energy and lowers the temperature of the fire.Halon has ozone-depleting properties. Due to this effect, the 1989 Montreal Protocol (formally called the “Montreal Protocol on Substances That Deplete the Ozone Layer”) banned production and consumption of new halon in developed countries by January 1, 1994.

Recommended replacements for halon include the following systems: • Argon • FE-13 • FM-200

CO2, halon, and halon substitutes such as FM-200 are considered gas-based systems. All gas systems should use a countdown timer (both visible and audible) before gas is released. This is primarily for safety reasons, to allow personnel evacuation before release. A secondary effect is to allow personnel to stop the release in case of false alarm.

Water is usually the recommended fire suppression agent. Water (in the absence of electricity) is the safest suppression agent for people.

Dry pipe systems also have closed sprinkler heads: the difference is the pipes are filled with compressed air. The water is held back by a valve that remains closed as long as sufficient air pressure remains in the pipes. As the dry pipe sprinkler heads open, the air pressure drops in each pipe, allowing the valve to open and send water to that head.

Dry pipes are often used in areas where water may freeze, such as parking garages.

Deluge systems are similar to dry pipes, except the sprinkler heads are open and larger than dry pipe heads. The pipes are empty at normal air pressure; the water is held back by a deluge valve.