MAC Methods for OODBMS Security

Dr. Bhavani Thuraisingham of MITRE Corp. proposed in 1989 a mandatory security policy called SORION. This model extends the ORION model to encompass mandatory access control. The model specifies subjects, objects, and access modes within the system, and it assigns security/sensitivity levels to each entity. Certain properties regulate the assignment of the sensitivity levels to each of the subjects, objects, and access modes. In order to gain access to the instance variables and methods in the objects, certain properties that are based on the various sensitivity levels must be satisfied.

A similar approach has been proposed in the Millen-Lunt model. This model, developed by Jonathan K. Millen of MITRE Corp. and Teresa Lunt of SRI/DARPA (Defense Advanced Research Projects Agency), also uses the assignment of sensitivity levels to the objects, subjects, and access modes within the data base. In the Millen-Lunt model, the properties that regulate the access to the information are specified as axioms within the model. This model further attempts to classify information according to three different cases:

•  The data itself is classified.

•  The existence of the data is classified.

•  The reason for classifying the information is also classified.

These three classifications broadly cover the specifics of the items to be secured within the data base; however, the classification method also greatly increases the complexity of the system.

The SODA Model

Dr. Thomas F. Keefe of Pennsylvania State University proposes a model called Secure Object-Oriented Data Base (SODA). The SODA model was one of the first models to address the specific concepts in the OO paradigm. It is often used as a standard example of secure object-oriented models from which other models are compared.

The SODA model complies with MAC properties and is executed in a multilevel security system. SODA assigns classification levels to the data through the use of inheritance. However, multiple inheritance is not supported in the SODA model.

Similar to other secure models, SODA assigns security levels to subjects in the system and sensitivity levels to objects. The security classifications of subjects are checked against the sensitivity level of the information before access is allowed.

Polyinstantiation

Unlike many current secure object-oriented models, SODA allows the use of polyinstantiation as a solution to the multiparty update conflict. This problem arises when users with different security levels attempt to use the same information. The variety of clearances and sensitivities in a secure data base system result in conflicts between the objects that can be accessed and modified by the users.

Through the use of polyinstantiation, information is located in more than one location, usually with different security levels. Obviously, the more sensitive information is omitted from the instances with lower security levels.

Although polyinstantiation solves the multiparty update conflict problem, it raises a potentially greater problem in the form of ensuring the integrity of the data within the data base. Without some method of simultaneously updating all occurrences of the data in the data base, the integrity of the information quickly disappears. In essence, the system becomes a collection of several distinct data base systems, each with its own data.

CONCLUSION

The move to object-oriented DBMSs is likely to continue for the foreseeable future. Because of the increasing need for security in distributed processing environments, the expanded selection of tools available for securing information in this environment should be used fully to ensure that the data are as secure as possible. In addition, with the continuing dependence on distributed data the security of these systems must be fully integrated into existing and future network security policies and procedures.

The techniques that are ultimately used to secure commercial OODBMS implementations will depend in large part on the approaches promoted by the leading data base vendors. However, the applied research that has been conducted to date is also laying the groundwork for the security components that will in turn be incorporated in the commercial OODBMSs.