International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 5, May - 2013 Database Security & Access Control Models: A Brief Overview Kriti, Indu Kashyap CSE Dept. Manav Rachna International University, Faridabad, India Abstract 1.1 Threats to Database Security Database security is a growing concern evidenced A threat can be identified with a hostile agent by increase in number of reported incidents of loss who either accidently or intentionally gains an of or unauthorized exposure of sensitive data. unauthorized access to the protected database Security models are the basic theoretical tool to resource [3] [4]. start with when developing a security system. These In organizations there are top ten type of threats models enforce security policies which are are recognized with can’t only increase the risk of governing rules adopted by any organization. database exposure but also cause disastrous Access control models are security models whose consequences on the entire organization. Some of purpose is to limit the activities of legitimate users. these threats are described below [19]: The main types of access control include discretionary, mandatory and role based. All the Threat 1 - Excessive Privilege Abuse three techniques have their drawbacks and When users (or applications) are granted benefits. The selection of a proper access control database access privileges that exceed the model depends on the requirement and the type of requirements of their job function, these privileges attacks to which the system is vulnerable. The aim may be abused for malicious purpose. of this paper is to give brief information on database security threats and discusses the three Threat 2 - Legitimate Privilege Abuse models of access control DAC, MAC & RBAC. Users may also abuse legitimate database privileges for unauthorized purposes. Threat 3 - Platform Vulnerabilities 1. Introduction Vulnerabilities in underlying operating systems Information is a critical resource in today’s may lead to unauthorized access, data corruption, enterprise, whether it is industrial, commercial,IJERT IJERTor denial of service. educational etc. As the organizations increase their adoption of database systems as the key data Threat 4 - SQL Injection management technology for day-to-day operations In a SQL injection attack, attacker typically and decision making, the security of data becomes inserts unauthorized database statements into a crucial [14]. The Defence Information System vulnerable SQL data channel. Agency of US Department of defence states that database security should provide controlled, Threat 5 - Denial of Service protected access to the contents of database as well Denial of Service (DOS) is a general attack as preserve the integrity, consistency and overall category in which access data is denied to intended quality of the data [2]. users. Database security encompasses three constructs [1]: confidentiality, integrity, and availability. Threat 6 - Weak Authentication Confidentiality: Protection of data from Weak authentication schemes allow attackers to unauthorized disclosure. assume the identity of legitimate database users by stealing or otherwise obtaining login credentials. Integrity: Prevention from unauthorized data access. 1.2 Database Security Policies To eliminate threats, it is necessary to define Availability: Identification and recovery from proper security policy. Security policies are hardware and software errors or malicious governing principles adopted by organizations [3]. activity resulting in the denial of data They capture the security requirements of an availability. organization, specify what security properties the system must provide and describe steps an organization must take to achieve security. The following list gives features of a security policy for databases: www.ijert.org 743 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 5, May - 2013 Access Control Policy: These policies ensure There are two classes of resources in any that direct access to the system objects should computer system: (active) subjects and (passive) proceed according to the privileges and the objects. The ways a subject access an object are access rules. called access privileges. Access privileges allow Inference Policy: These policies specify how subjects to either manipulate objects (read, write, to protect classified information from execute, etc.) or modify the access control disclosure when the information is released information (transfer ownership, grant and revoke indirectly in the form of statistical data. privileges, etc.). User identification/authentication policy: The access control may be based on different This policy indicates the requirements for policies which in turn follows different principles. correct identification of users. The user The choice of a security policy is important identification is the basis of every security because it influences the flexibility, usability, and mechanism. A user is allowed to access data performance of the system. The principles on after identification as an authorized user only. which policies are based are as follows [3]: Accountability and audit policy: This policy Minimum vs. Maximum privilege principle: provides the requirements for the record According to this subjects should use the keeping of all accesses to the database. minimum set of privileges necessary for their Consistency policy: This policy defines the activity. The opposite of this is maximum state in which the database is considered valid privilege principle which is based on the or correct and includes operational, semantic principle of maximum availability of data in a and physical integrity of database. database. Open vs. Closed system principle: In an open 1.3 Database Security Models system, all accesses that are not explicitly Security models are the formal description of forbidden are allowed. While in a closed security policies. Security models are useful tools system, all accesses are allowed only if for evaluating and comparing security policies [6]. explicitly authorized. A closed system is Security models allow us to test security policies inherently more secure. for completeness and consistency. They describe Centralized vs. Decentralized what mechanisms are necessary to implement a administration principle: The principle security policy. addresses the issue who is responsible for the Security models are described in terms of the maintenance and management of privileges in following elements: the access control model. In centralized Subjects: Entities that request access to administration, a single authority controls all objects. IJERTIJERTsecurity aspects of the system, while in Objects: Entities for which access request is decentralized system different authorities being made by subjects. control different portions of the database. Access Modes: Type of operation performed by subject on object (read, write, create etc.). Access control is enforced by a reference monitor which mediates every attempted access by Policies: Enterprise wide accepted security a user to objects in the system. The reference rules. monitor consults an authorization database in order Authorizations: Specification of access to determine if the user attempting to do an modes for each subject on each object. operation is actually authorized to perform that Administrative Rights: Who has rights in operation. Authorizations in this database are system administration and what administered and maintained by a security responsibilities administrators have. administrator as shown in fig 1. The administrator Axioms: Basic working assumptions. sets these authorizations on the basis of the security policy. 2. Access Control Access control is different from authentication. The purpose of access control is to limit the Authentication is a process of signing on to a actions or operations that a legitimate user of a computer system by providing an identifier and a computer system can perform. Access control password. So, correctly establishing the identity of constraints what a user can do directly, as well as the user is the responsibility of the authentication what programs executing on behalf of the users are service. On the other hand, access control assumes allowed to do. In this way access control seeks to that authentication of the user has been successfully prevent activity that could lead to a breach of verified prior to enforcement of access control via a security. reference monitor. www.ijert.org 744 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 5, May - 2013 Fig 1: Access Control and Security Services 3. Discretionary Access Control (DAC) privilege p on table t, with or without grant option. Specify the rules, under which subjects can, at Every time a privilege is revoked from a user, a their discretion, create and delete objects, and grant recursive revocation may take place to delete all and revoke authorizations for accessing objects to authorizations which would have not existed had others [6]. That is: the revokee never received any authorizations for Govern the access of users to information on the the privilege on the table from the revoker. basis of user’s identity and predefined discretionary rules” defined by security administrator. To illustrate this concept, consider the The rules specify, for each user and object in the consequence of grant operations for privilege p on system,