CISSPillsDOMAIN 1: Access Control

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Table of Contents Overview Access Control Flow Access Control Elements Authentication Factors

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Overview

Access Controls relate to those mechanisms used to regulate how resources can be accessed by entities. They protect systems from unauthorised access.Access is the flow of information between a subject and an object. Subject: is an active entity that request access to an object or data

within an object. Subjects can be users, programs, processes, computers, etc.;

Object: is a passive element, which contains information or needed functionalities. Objects can be databases, files, printers, storage media, etc.

Sometimes the same entity could behave as a subject (requesting information), but also as an object (being accessed by a subject). The rule of thumb to distinguish the role being provided by an entity is as follows:The subject is always the active entity that receives the information or data, whilst the object is always the passive entity that provides or host the information or data.

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Access Control Flow

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Access Control ElementsThe security elements that work together to support access control are grouped into four types: identification, authentication, authorisation and accountability. Identification: is the mechanism by which a subject claims an identity, for

instance using a username or an account number; Authentication: is the mechanism by which a subject proves a claimed identify,

for example by providing a password; Authorisation: is the mechanism by which subjects are granted only the

privileges they are entitled to. Access Control Lists (ACLs) are a typical example of mechanism to enforce authorisation: if they determine that a subject may access the resource, they authorise the subject. It’s worth noting that just because a subject is authenticated, it is not given access to anything and everything.

Accountability: is accomplished by implementing auditing, which helps keeping track of the subject’s activities (e.g. when a subject accesses, modifies or deletes an object). Audit trails support accountability by logging the activities performed by a subject over an object.

All the four elements above must exist for an access control system to be effective.

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Access Controls Elements (cont’d)

Identification

Authentication

Accountability

Subject

Authorisation

e.g. Username

e.g. Password

e.g. ACLs

e.g. audit logs

Object

Access

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Autenthication Factors

Type 1: is something you know. It’s any string of characters that can be memorised and typed on a keyboard (e.g. passwords, PINs, etc.);

Type 2: is something you have. It’s a physical device users must have in their possession during the authentication (e.g. tokens, smart cards, etc.);

Type 3: is something you are. It’s a trait, either physical or behavioural, that uniquely identifies a person (e.g. fingerprints, retina patterns, keystroke dynamics, etc.)

Strong Authentication (also known as multifactor authentication) is when two out of the three factors are used during the authentication.

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