Section 5.4: Basics of Data Sensitivity and Security

A company possesses different kinds of data that is for the use of different types of people in the organization. The information classification is therefore very important for a company and based on this classification, distribution policies should be developed by the companies. The information can be classified as:

Public distribution: This information is distributed by the company to larger public or specific individuals who need it. It includes the financial statements of a private company.
Limited distribution: This information is private to the company but the company needs to share it limitedly. For example, the information that a company needs to provide to a bank, to seek loans. This information should not be disclosed to customers and business rivals because the rivals may take undue advantage of the information and the customers can get scared of investing money.
Full distribution: This includes information such as marketing material or the brochures of the company. This also includes annual reports to stockholders.

Different types of users are involved in the information process. A clear set of roles and responsibilities allows the management of information batter. The different types of roles are:

Owner: The owner of the information is most commonly the senior manager or the other decision makers. He is responsible for the protection of the information. Usually the owner delegates the rights of the information to other individuals.
Custodian: The custodians of data are the people who are responsible for the maintenance and the protection of data. For example people such as network administrators and backup operators.
User: User is the person in an organization who uses the data. The user may use the data for input, output, perform editing of data or use the data for other functions.
Security professional: The security professionals ensure the security of data. They may include people like testers, who test data for any security lapses, investigators, who investigate a security related problem in data, and policy developers, who create security policies related to data security.
Auditor: Auditors ensure that the security policies, guidelines, and practices are being followed in the company properly. They help to identify the deficiencies in the security.

Section 5.4.1: Information Access Controls

The information access control methods enable you to ensure that the network users are allowed to access only the information they are authorized to. The access controls are implemented with the help of security policies in an organization. There are a few access control models that help an organization to implement them. The models are based on the concepts of implicit denies and the least privilege.

The implicit denies are where you implicitly lock certain users to access certain information. You can create deny and allow permissions to deny and allow access to information. The least privilege is where you assign only limited permissions to users to let them do their work.

The access control models are:

Bell-La-Padula: The Bell-LaPadula Model (BLM) is the multi-level model created for government and military applications to implement access control by Bell and LaPadula. This Model supports mandatory access control by determining the access rights from the security levels associated with subjects and objects. It is concerned with information confidentiality and ensures that the subjects reading from an object must have higher a security class than the object and the objects being written to by a subject must have higher security class than the subject. A problem with this model is it does not deal with the integrity of data.
Biba Model: The Biba model was published one year after the Bell La-Padula model was published to remove the inability of the Bell-LaPadula model to deal with integrity of data. This model emphasizes on the information integrity and is designed in such a way that ensures that the subjects may not corrupt data in a level ranked higher than the subject, or get corrupted by data from a lower level than the subject. In the Biba model, users can only create content at or below their own integrity level and users can only view content at or above their own integrity level
Clark-Wilson Model: The Clark-Wilson model is different from other models. It does not focus on subjects and objects rather it introduce a third access element called programs, which prevents unauthorized users from modifying data or programs. This model also focuses on internal and external consistency of data by using integrity verification and transformation procedures. The Clark-Wilson model addresses all the three goals of integrity.
Information Flow Model: Although, both Bell-LaPadula Model and Biba model are information flow model because they deal with the flow of information, Information Flow Model is however different. This is because it is concerned will the flow of information in all the direction and not just up or down. This model prevents an operation from occurring if it is illegal.
Noninterference Model: The Noninterference Model ensures that the high level security functions do not interfere with the lower-level functions. This prevents the lower level user to get affected by the changes made to the higher level of a system.