Research the Bell-Lapadula access control model or another lattice-based model and compare the model to one other model. A discussion question will be posted prior to the start of the assigned unit

Bell–LaPadula model was developed originally for the U.S. Department of Defense to enforce the access controls in the government and military applications. It consists of two rules: the Simple Security Property and the Security Property. The simple security property rule states that there is no read up, hence the subject at a certain level of classification cannot read an object which is at the higher certain level of classification. The security property states that there is no write down, hence the subject at the higher certain level of classification, cannot write to the ones that are at the lower level of classification ("Lapadula Model"). Bell-Lapadula describes the levels of security and clearance, when apportioning the access controls for the military or government applications in terms of subjects and objects. Subject can be defined as an individual human being, device, application, organization, or a computer system, which is assigned a security clearance and the current clearance level, and which cannot exceed its assigned clearance level. Therefore, the subject is allowed to only level down its assigned security clearance, but is not allowed to level up. Objects which can be defined as a portion of the computer memory, files, documents, datasets, are also assigned a security level based on the information sensitivity level that they are composed of. Therefore, the subject can only access the objects which are presented in those levels the same as the subject's security level (FInjan, 2017). 

Bell-Lapadula focuses on both the mandatory as well as the discretionary access control. This mandatory access control is a means of restricting access to the objects based on the sensitivity level of the information presented in the objects, and the formal authorization of the subjects to access those sensitive information. There is also the discretionary access control which restricts access to the objects based on the identity of the subject or group to which they belong (Dewan). However, this model assumes that the security level of the object remains static, and is most relevant for systems with large static security levels.

The other lattice based model is the Biba integrity model, which was created as a supplement to the Bell-Lapadula model, and it addresses the concerns about the system and the integrity of the information. While Bell-Lapadula focused on the confidentiality aspect, this model focuses on integrity. Integrity is important when it comes to data security, which simply means that the authorized users do not make unauthorized changes or modifications to the information, and the unauthorized users don’t make changes to the information and to ensure that the information remains consistent. Biba model was created as under the Bell-Lapadula model, it was possible for a user from lower classification level to easily overwrite or modify the information of higher classification, as there was an absence of a defined integrity policy. This Biba model allows the levels of security determined by the Bell-Lapadula model, the integrity level which are determined by the Biba model, as well as the knowledge which is established by the military’s need to know access privileges. Biba model also has a hierarchical structure, which compares the level of integrity of the files, people and processes. The objects and subjects concepts are defined in a similar way in the Biba model as in the Bell-Lapadula model. The Biba model uses these three properties to protect the objects from being modified. The first one is the simple integrity which states that the subject presented at one integrity level is not permitted to read an object at the lower integrity level, hence no read down. The second one is the star integrity which states that the object at one integrity level is not allowed to write to an object at the higher integrity level, hence no write up. The third one is invocation, which states that the subject one level of integrity is prohibited from invoking or calling up the subject which is at the higher level of integrity. Hence, the ones that are at higher integrity levels are isolated from the lower integrity levels, hence reducing modification and unnecessary or unauthorized changes. Therefore, the new objects created are given the same level of integrity as the processes that created them (FInjan, 2017).

References

Lapadula Model. (n.d.). Retrieved from

https://www.sciencedirect.com/topics/computer-science/lapadula-model 

FInjan. (2017, March 6). Access Control Systems - A Closer Look at the Bell-LaPadula Model. Retrieved from 

https://blog.finjan.com/access-control-systems-a-closer-look-at-the-bell-lapadula-model/ 

Dewan, P. (n.d.). Bell LaPadula Model. Retrieved from

http://www.cs.unc.edu/~dewan/242/f96/notes/prot/node13.html 

FInjan. (2017, March 6). A Closer Look at Data Security and the Biba Integrity Model. Retrieved from

https://blog.finjan.com/biba-integrity-model/