Access control

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For access control on a highway, see controlled-access highway. For standardized forms of names in a library catalog, see authority control.
A soldier allows a driver to enter a military base.

In the fields of physical security and information security, access control is the selective restriction of access to a place or other resource.[1] The act of accessing may mean consuming, entering, or using. Permission to access a resource is called authorization.

Locks and login credentials are two analogous mechanisms of access control.

Physical security[edit]

Main article: Physical security
Underground entrance to the New York City Subway system
Physical security access control with a hand geometry scanner
Example of fob based access control using an ACT reader

Geographical access control may be enforced by personnel (e.g., border guard, bouncer, ticket checker), or with a device such as a turnstile. There may be fences to avoid circumventing this access control. An alternative of access control in the strict sense (physically controlling access itself) is a system of checking authorized presence, see e.g. Ticket controller (transportation). A variant is exit control, e.g. of a shop (checkout) or a country.[citation needed]

The term access control refers to the practice of restricting entrance to a property, a building, or a room to authorized persons. Physical access control can be achieved by a human (a guard, bouncer, or receptionist), through mechanical means such as locks and keys, or through technological means such as access control systems like the mantrap. Within these environments, physical key management may also be employed as a means of further managing and monitoring access to mechanically keyed areas or access to certain small assets.[citation needed]

Physical access control is a matter of who, where, and when. An access control system determines who is allowed to enter or exit, where they are allowed to exit or enter, and when they are allowed to enter or exit. Historically, this was partially accomplished through keys and locks. When a door is locked, only someone with a key can enter through the door, depending on how the lock is configured. Mechanical locks and keys do not allow restriction of the key holder to specific times or dates. Mechanical locks and keys do not provide records of the key used on any specific door, and the keys can be easily copied or transferred to an unauthorized person. When a mechanical key is lost or the key holder is no longer authorized to use the protected area, the locks must be re-keyed.[citation needed]

Electronic access control uses computers to solve the limitations of mechanical locks and keys. A wide range of credentials can be used to replace mechanical keys. The electronic access control system grants access based on the credential presented. When access is granted, the door is unlocked for a predetermined time and the transaction is recorded. When access is refused, the door remains locked and the attempted access is recorded. The system will also monitor the door and alarm if the door is forced open or held open too long after being unlocked.[citation needed]

Access control system operation[edit]

When a credential is presented to a reader, the reader sends the credential’s information, usually a number, to a control panel, a highly reliable processor. The control panel compares the credential's number to an access control list, grants or denies the presented request, and sends a transaction log to a database. When access is denied based on the access control list, the door remains locked. If there is a match between the credential and the access control list, the control panel operates a relay that in turn unlocks the door. The control panel also ignores a door open signal to prevent an alarm. Often the reader provides feedback, such as a flashing red LED for an access denied and a flashing green LED for an access granted.[citation needed]

The above description illustrates a single factor transaction. Credentials can be passed around, thus subverting the access control list. For example, Alice has access rights to the server room, but Bob does not. Alice either gives Bob her credential, or Bob takes it; he now has access to the server room. To prevent this, two-factor authentication can be used. In a two factor transaction, the presented credential and a second factor are needed for access to be granted; another factor can be a PIN, a second credential, operator intervention, or a biometric input.[citation needed]

There are three types (factors) of authenticating information:[2]

Multiple Electronic Lock (passwords, cards)

Passwords are a common means of verifying a user's identity before access is given to information systems. In addition, a fourth factor of authentication is now recognized: someone you know, whereby another person who knows you can provide a human element of authentication in situations where systems have been set up to allow for such scenarios. For example, a user may have their password, but have forgotten their smart card. In such a scenario, if the user is known to designated cohorts, the cohorts may provide their smart card and password, in combination with the extant factor of the user in question, and thus provide two factors for the user with the missing credential, giving three factors overall to allow access.[citation needed]

Credential[edit]

A credential is a physical/tangible object, a piece of knowledge, or a facet of a person's physical being, that enables an individual access to a given physical facility or computer-based information system. Typically, credentials can be something a person knows (such as a number or PIN), something they have (such as an access badge), something they are (such as a biometric feature) or some combination of these items. This is known as multi-factor authentication. The typical credential is an access card or key-fob, and newer software can also turn users' smartphones into access devices.[3] There are many card technologies including magnetic stripe, bar code, Wiegand, 125 kHz proximity, 26-bit card-swipe, contact smart cards, and contactless smart cards. Also available are key-fobs, which are more compact than ID cards, and attach to a key ring. Biometric technologies include fingerprint, facial recognition, iris recognition, retinal scan, voice, and hand geometry.[4] The built-in biometric technologies found on newer smartphones can also be used as credentials in conjunction with access software running on mobile devices.[5] In addition to older more traditional card access technologies, newer technologies such as Near field communication (NFC) and Bluetooth low energy also have potential to communicate user credentials to readers for system or building access.[6][7]

Access control system components[edit]

An access control point, which can be a door, turnstile, parking gate, elevator, or other physical barrier, where granting access can be electronically controlled. Typically, the access point is a door. An electronic access control door can contain several elements. At its most basic, there is a stand-alone electric lock. The lock is unlocked by an operator with a switch. To automate this, operator intervention is replaced by a reader. The reader could be a keypad where a code is entered, it could be a card reader, or it could be a biometric reader. Readers do not usually make an access decision, but send a card number to an access control panel that verifies the number against an access list. To monitor the door position a magnetic door switch can be used. In concept, the door switch is not unlike those on refrigerators or car doors. Generally only entry is controlled, and exit is uncontrolled. In cases where exit is also controlled, a second reader is used on the opposite side of the door. In cases where exit is not controlled, free exit, a device called a request-to-exit (REX) is used. Request-to-exit devices can be a push-button or a motion detector. When the button is pushed, or the motion detector detects motion at the door, the door alarm is temporarily ignored while the door is opened. Exiting a door without having to electrically unlock the door is called mechanical free egress. This is an important safety feature. In cases where the lock must be electrically unlocked on exit, the request-to-exit device also unlocks the door.[citation needed]

Access control topology[edit]

Typical access control door wiring
Access control door wiring when using intelligent readers

Access control decisions are made by comparing the credential to an access control list. This look-up can be done by a host or server, by an access control panel, or by a reader. The development of access control systems has seen a steady push of the look-up out from a central host to the edge of the system, or the reader. The predominant topology circa 2009 is hub and spoke with a control panel as the hub, and the readers as the spokes. The look-up and control functions are by the control panel. The spokes communicate through a serial connection; usually RS-485. Some manufactures are pushing the decision making to the edge by placing a controller at the door. The controllers are IP enabled, and connect to a host and database using standard networks.[citation needed]

Types of readers[edit]

Access control readers may be classified by the functions they are able to perform:[citation needed]

Some readers may have additional features such as an LCD and function buttons for data collection purposes (i.e. clock-in/clock-out events for attendance reports), camera/speaker/microphone for intercom, and smart card read/write support.[citation needed]

Access control readers may also be classified by their type of identification technology.[citation needed]

Access control system topologies[edit]

Access control system using serial controllers

1. Serial controllers. Controllers are connected to a host PC via a serial RS-485 communication line (or via 20mA current loop in some older systems). External RS-232/485 converters or internal RS-485 cards have to be installed, as standard PCs do not have RS-485 communication ports.[citation needed]

Advantages:[citation needed]

Disadvantages:[citation needed]

Access control system using serial main and sub-controllers

2. Serial main and sub-controllers. All door hardware is connected to sub-controllers (a.k.a. door controllers or door interfaces). Sub-controllers usually do not make access decisions, and instead forward all requests to the main controllers. Main controllers usually support from 16 to 32 sub-controllers.

Advantages:[citation needed]

Disadvantages:[citation needed]

Access control system using serial main controller and intelligent readers

3. Serial main controllers & intelligent readers. All door hardware is connected directly to intelligent or semi-intelligent readers. Readers usually do not make access decisions, and forward all requests to the main controller. Only if the connection to the main controller is unavailable, will the readers use their internal database to make access decisions and record events. Semi-intelligent reader that have no database and cannot function without the main controller should be used only in areas that do not require high security. Main controllers usually support from 16 to 64 readers. All advantages and disadvantages are the same as the ones listed in the second paragraph.

Access control systems using serial controllers and terminal servers

4. Serial controllers with terminal servers. In spite of the rapid development and increasing use of computer networks, access control manufacturers remained conservative, and did not rush to introduce network-enabled products. When pressed for solutions with network connectivity, many chose the option requiring less efforts: addition of a terminal server, a device that converts serial data for transmission via LAN or WAN.

Advantages:[citation needed]

Disadvantages:[citation needed]

All the RS-485-related advantages and disadvantages also apply.

Access control system using network-enabled main controllers

5. Network-enabled main controllers. The topology is nearly the same as described in the second and third paragraphs. The same advantages and disadvantages apply, but the on-board network interface offers a couple of valuable improvements. Transmission of configuration and user data to the main controllers is faster, and may be done in parallel. This makes the system more responsive, and does not interrupt normal operations. No special hardware is required in order to achieve redundant host PC setup: in the case that the primary host PC fails, the secondary host PC may start polling network controllers. The disadvantages introduced by terminal servers (listed in the fourth paragraph) are also eliminated.

Access control system using IP controllers

6. IP controllers. Controllers are connected to a host PC via Ethernet LAN or WAN.

Advantages:[citation needed]

Disadvantages:[citation needed]

Access control system using IP readers

7. IP readers. Readers are connected to a host PC via Ethernet LAN or WAN.

Advantages:[citation needed]

Disadvantages:[citation needed]

The advantages and disadvantages of IP controllers apply to the IP readers as well.

Security risks[edit]

Access control door wiring when using intelligent readers and IO module

The most common security risk of intrusion through an access control system is by simply following a legitimate user through a door, and this is referred to as "tailgating". Often the legitimate user will hold the door for the intruder. This risk can be minimized through security awareness training of the user population, or more active means such as turnstiles. In very high security applications this risk is minimized by using a sally port, sometimes called a security vestibule or mantrap, where operator intervention is required presumably to assure valid identification.[citation needed]

The second most common risk is from levering a door open. This is surprisingly simple and effective on most doors. The lever could be as small as a screwdriver or big as a crow bar. Fully implemented access control systems include forced door monitoring alarms. These vary in effectiveness, usually failing from high false positive alarms, poor database configuration, or lack of active intrusion monitoring.[citation needed]

Similar to levering is crashing through cheap partition walls. In shared tenant spaces the divisional wall is a vulnerability. A vulnerability along the same lines is the breaking of sidelights.[citation needed]

Spoofing locking hardware is fairly simple and more elegant than levering. A strong magnet can operate the solenoid controlling bolts in electric locking hardware. Motor locks, more prevalent in Europe than in the US, are also susceptible to this attack using a doughnut shaped magnet. It is also possible to manipulate the power to the lock either by removing or adding current.[citation needed]

Access cards themselves have proven vulnerable to sophisticated attacks. Enterprising hackers have built portable readers that capture the card number from a user’s proximity card. The hacker simply walks by the user, reads the card, and then presents the number to a reader securing the door. This is possible because card numbers are sent in the clear, no encryption being used.[citation needed]

Finally, most electric locking hardware still have mechanical keys as a fail-over. Mechanical key locks are vulnerable to bumping.[citation needed]

The need-to-know principle[edit]

The need to know principle can be enforced with user access controls and authorization procedures and its objective is to ensure that only authorized individuals gain access to information or systems necessary to undertake their duties. See Principle of least privilege.[citation needed]

Computer security[edit]

Further information: Computer access control

In computer security, general access control includes authorization, authentication, access approval, and audit. A more narrow definition of access control would cover only access approval, whereby the system makes a decision to grant or reject an access request from an already authenticated subject, based on what the subject is authorized to access. Authentication and access control are often combined into a single operation, so that access is approved based on successful authentication, or based on an anonymous access token. Authentication methods and tokens include passwords, biometric scans, physical keys, electronic keys and devices, hidden paths, social barriers, and monitoring by humans and automated systems.[citation needed]

In any access-control model, the entities that can perform actions on the system are called subjects, and the entities representing resources to which access may need to be controlled are called objects (see also Access Control Matrix). Subjects and objects should both be considered as software entities, rather than as human users: any human users can only have an effect on the system via the software entities that they control.[citation needed]

Although some systems equate subjects with user IDs, so that all processes started by a user by default have the same authority, this level of control is not fine-grained enough to satisfy the principle of least privilege, and arguably is responsible for the prevalence of malware in such systems (see computer insecurity).[citation needed]

In some models, for example the object-capability model, any software entity can potentially act as both subject and object.[citation needed]

As of 2014, access-control models tend to fall into one of two classes: those based on capabilities and those based on access control lists (ACLs).

Both capability-based and ACL-based models have mechanisms to allow access rights to be granted to all members of a group of subjects (often the group is itself modeled as a subject).[citation needed]

Access control systems provide the essential services of authorization, identification and authentication (I&A), access approval, and accountability where:[citation needed]

Access Control[edit]

Access to accounts can be enforced through four major types of controls.[9]

  1. Mandatory Access Control (MAC)
    In MAC, users do not have much freedom to determine who has access to their files. For example, security clearance of users and classification of data (as confidential, secret or top secret) are used as security labels to define the level of trust.
  2. Discretionary Access Control (DAC)
    In DAC, the data owner determines who can access specific resources. For example, a system administrator may create a hierarchy of files to be accessed based on certain permissions.
  3. Role-Based Access Control (RBAC)
    RBAC allows access based on the job title. For example, a human resources specialist should not have permissions to create network accounts; this should be a role reserved for network administrators.
  4. Rule-Based Access Control
    An example of this would be only allowing students to use the labs during a certain time of the day.

Telecommunication[edit]

In telecommunication, the term access control is defined in U.S. Federal Standard 1037C[10] with the following meanings:

  1. A service feature or technique used to permit or deny use of the components of a communication system.
  2. A technique used to define or restrict the rights of individuals or application programs to obtain data from, or place data onto, a storage device.
  3. The definition or restriction of the rights of individuals or application programs to obtain data from, or place data into, a storage device.
  4. The process of limiting access to the resources of an AIS (Automated Information System) to authorized users, programs, processes, or other systems.
  5. That function performed by the resource controller that allocates system resources to satisfy user requests.

This definition depends on several other technical terms from Federal Standard 1037C.

Public policy[edit]

In public policy, access control to restrict access to systems ("authorization") or to track or monitor behavior within systems ("accountability") is an implementation feature of using trusted systems for security or social control.

See also[edit]

References[edit]

  1. ^ RFC 4949
  2. ^ Federal Financial Institutions Examination Council (2008). "Authentication in an Internet Banking Environment". Retrieved 2009-12-31. 
  3. ^ "MicroStrategy’s office of the future includes mobile identity and cybersecurity". Washington Post. 2014-04-14. Retrieved 2014-03-30. 
  4. ^ biometric access control technology overview
  5. ^ "iPhone 5S: A Biometrics Turning Point?". BankInfoSecurity.com. 2013-09-16. Retrieved 2014-03-30. 
  6. ^ "NFC access control: cool and coming, but not close". Security Systems News. 2013-09-25. Retrieved 2014-03-30. 
  7. ^ "Ditch Those Tacky Key Chains: Easy Access with EC Key". Wireless Design and Development. 2012-06-11. Retrieved 2014-03-31. 
  8. ^ isonas.com
  9. ^ http://www.evolllution.com/media_resources/cybersecurity-access-control/
  10. ^ http://www.its.bldrdoc.gov/fs-1037/other/a.pdf

External links[edit]