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Security+ (SY0-401) Cram Notes

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5.2 Explain the fundamental concepts and best practices related to authentication, authorization and access control

Computer based access controls prescribe not only who or what process may have access to a given resource, but also the type of access that is permitted. These controls may be implemented in the computer system or in external devices. Different types of access control are:

Mandatory Access Control (MAC): secures information by assigning sensitivity labels on objects (resources) and comparing this to the level of sensitivity a subject (user) is operating at. MAC ensures that all users only have access to that data for which they have matching or greater security label (or security clearance). In general, MAC access control mechanisms are more secure than DAC. MAC is usually appropriate for extremely secure systems including multilevel secure military applications or mission critical data applications.

Discretionary Access Control (DAC): Discretionary Access Control (DAC) is a means of restricting access to information based on the identity of users and/or membership in certain groups. Access decisions are typically based on the authorizations granted to a user based on the credentials he presented at the time of authentication (user name, password, hardware/software token, etc.). In most typical DAC models, the owner of information or any resource is able to change its permissions at his discretion. DAC has the drawback of the administrators not being able to centrally manage these permissions on files/information stored on the web server.

Role Based Access Control (RBAC): In Role-Based Access Control (RBAC), access decisions are based on an individual's roles and responsibilities within the organization. For instance, in a corporation, the different roles of users may include those such as chief executive, manager, executive, and clerk. Obviously, these members require different levels of access in order to perform their functions, but also the types of web transactions and their allowed context vary greatly depending on the security policy. In Role Based Access Control, the administrator sets the roles. Therefore, this type of access control is sometimes considered as a subset of MAC.

Rule Based Access Control (RBAC): The access to a resource in Rule Based Access Control is based a set of rules. ACLs (Access Control Lists) are used for this type of access control. In Rule Based Access Control, the administrator sets the rules. Therefore, this type of access control is sometimes considered as a subset of MAC.

Authentication Types

Mutual authentication: Here both the server and client computers authenticate each other. This type of authentication is more secure than one-way authentication, where only the client is authenticated.

Multifactor authentication: Here two or more number of authentication methods are used for granting access to a resource. Usually, it combines a password with that of a biometric authentication.

Biometric authentication: Biometric authentication uses measurable physical attributes of a human being such as signature, fingerprint. A biometric authentication depends on the physical characteristic of a human being. It is not something that can be remembered. Usually, bio authentication is very secure, though not widely used due to cost constraints. Biometrics is the ability measure physical characteristics of a human such as fingerprints, speech etc. These measured values are then used for authentication purpose. Given below are few of the measurable quantities:

  • Fingerprint: Scans and matches finger print to a securely stored value.

  • Voiceprint: Identifies a person by measuring speech pattern.

  • Iris profile: Identifies a person by using Iris part of the eye.

  • Signature: Matches an individualís signature with the stored value.

CHAP: It is an authentication type that uses three-way handshake. The p asswords are transmitted in encrypted form ensuring security. Compare this with PAP, which transmits passwords in clear text.

Least privilege: It is a technical control. It specifies that individuals or processes are granted only those rights and permissions needed to perform their assigned tasks or functions. Rights and permissions are commonly assigned on servers, but rarely on mobile devices such as tablets and smart-phones.

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