Lesson 6: Database Security

6 Database Security Introduction Database security issues are often lumped together with data integrity issues, but the two concepts are really quite distinct. Security refers to the protection of data against unauthorized disclosure, alteration, or destruction; integrity refers to the accuracy or validity of that data. In simple terms: – Security means protecting the data against unauthorized users. – Integrity means protecting the data against authorized users. In both cases, system needs to be aware of certain constraints that users must not violate; in both cases those constraints must be specified in some suitable language, and must be maintained in the system catalog; and in both cases the DBMS must monitor user operations in order to ensure that the constraints are enforced. The main reason to clearly separate the discussion of the two topics is that integrity is regarded as absolutely fundamental but security as more of a secondary issue. 6.1 Database Security The person responsible for security of the database is usually database administrator (DBA). The database administrator must consider variety of potential threats to the system. Database administrators create authorization rules that define who can access what parts of database for what operations. Enforcement of authorization rules involves authenticating the user and ensuring that authorization rules are not violated by access requests. DBMS should support creation and storage of authorization rules and enforcement of authorization rules when users access a database. 6.1.1 General Considerations in Database Security There are numerous aspects to the security problem, some of them are: – Legal, social, and ethical aspects 1 – Physical controls – Policy questions – Operational problems – Hardware control – Operating system support – Issues that are the specific concern of the database system itself 6.1.2 Database Security threats Security threat can be broadly classified into accidental, intentional according to the way they occur. The accidental threats include human errors, errors in software, and natural or accidental disasters. Human errors include giving incorrect input, incorrect use of applications. Errors in software include incorrect application of security policies, denial of access to authorized users. Natural or accidental disasters include the damage of hardware or software. The intentional threat includes authorized users who abuse their privileges and authority, hostile agents like improper users executing improper reading or writing of data, legal use of applications can mask fraudulent purpose 6.1.3 Classification of Database Security The database security can be broadly classified into physical and logical security. Physical security. Physical security refers to the security of the hardware associated with the system and the protection of the site where the computer resides. Natural events such as fire, floods, and earthquakes can be considered as some of the physical threats. It is advisable to have backup copies of databases in the face of massive disasters. Logical security. Logical security refers to the security measures residing in the operating system or the DBMS designed to handle threats to the data. Logical security is far more difficult to accomplish. It is necessary to take care of the database security at the stage of database design. Few guidelines to build the most secure system are: a) Simple design. If the database is simple and easier to use, then the possibility that the data being corrupted by the authorized user is less. b) Normalization. The normalized database is almost free from update anomalies. It is harder to impose normalization on the relations after the database is in use. Hence, it is necessary to normalize the database at the design stage itself. c) Privileges. If no privileges are assumed by any user, there is less likelihood that a user will be able to gain illegal access. d) Unique views: Creating unique view for each user or group of users. A view promotes security by restricting user access to physical data. 2 6.2 Access Control Database access control is a method of allowing access to company’s sensitive data only to those people (database users) who are allowed to access such data and to restrict access to unauthorized persons. It includes two main components: authentication and authorization. Authentication is a method of verifying the identity of a person who is accessing your database. Note that authentication isn’t enough to protect data. An additional layer of security is required, authorization, which determines whether a user should be allowed to access the data or make a certain transaction or not. Without authentication and authorization, there is no data security. Obsolete access models include Discretionary Access Control (DAC) and Mandatory Access Control (MAC). Role Based Access Control (RBAC) is the most common method today, and the most recent model is Attribute Based Access Control (ABAC). 6.2.1 Discretionary Access Control (DAC) With DAC models, the data owner allows access. DAC is a means of assigning access rights based on user-specified rules. 6.2.2 Mandatory Access Control (MAC) MAC was developed using a nondiscretionary model, in which people are granted access based on an information clearance. MAC is a policy in which access rights are assigned based on central authority regulations. 6.2.3 Role Based Access Control (RBAC) RBAC grants access based on a user’s role and implements key security principles such as “least privilege” and “separation of privilege.” Thus, someone attempting to access information can only access data necessary for their role. 6.2.4 Attribute Based Access Control (ABAC) In ABAC, each resource and user are assigned a series of attributes. In this dynamic method, a comparative assessment of the user’s attributes, including time of day, position and location, are used to make a decision on access to a resource. 3