1. Chapter 9.3 Security Access Control
Saeid Motevali Alamoti
Georgia State University
Computer Science Department
Fall 2017

2. Agenda: Introduction General Issues in Access Control Firewalls
Access Control Matrix
Protection Domains
Firewalls
Secure Mobile Code
Protecting an Agent
Protecting the Target
Denial of Service
Protection Against DDoS
Conclusion

3. Introduction What is Access Control? Verifying access rights.
What is Authentication? Granting Access rights
Access control and Authentication- strongly related to each other

4. General Issues in Access Control:
Subject- Issues a request to access an object
Reference monitor- Records which subject may do what, and decides whether a subject is allowed to have a specific operation carried out
Object- Encapsulates its own state and implementing the operations on that state

5. Access Control Matrix:
Column- Object
Row- Subject
⋯ ⋮ ⋱ ⋮ ⋯

6. Access Control List (ACL)
Figure Comparison between ACLs and capabilities for protecting objects. (a) Using an ACL.

7. Access Control Capability:
Figure Comparison between ACLs and capabilities for protecting objects. (b) Using capabilities.

8. Protection Domains
Figure The hierarchical organization of protection domains as groups of users.

9. Figure 9-28. A common implementation of a firewall.
Firewalls
Figure A common implementation of a firewall.

10. Secure Mobile Code
Protecting an Agent
Protecting the Target

11. Protecting an Agent
Ajanta* provides three mechanisms that allow an agent's owner to detect that the agent has been tampered with
Read-only state
Append-only logs
Selective revealing of state to certain servers (array of data item)
*KARNIK, N. and TRIPATHI, A.: "Security in the Ajanta Mobile Agent System." Software - Practice & Experience, (31)4: , Apr

12. Figure 9-29. The organization of a Java sandbox.
Protecting the Target
Figure The organization of a Java sandbox.

13. Protecting the Target Cont.
Figure (a) A sandbox. (b) A playground.

14. Protecting the Target Cont (Java-Capabilities)
Figure The principle of using Java object references as capabilities.

15. Protecting the Target Cont (Java-Extended)
Figure The principle of stack introspection.

16. Denial of Service
DoS- Attempts to prevent from accessing the resources
DDoS- A huge collection of processes jointly attempt to bring down a networked service
Bandwidth depletion
Resource depletion
Bandwidth depletion can be accomplished by simply sending many messages to a single machine. The effect is that normal messages will hardly be able to reach the receiver.
Resource depletion attacks concentrate on letting the receiver use up resources on otherwise useless messages. A well-known resource-depletionattack is TCP SYN-flooding.

17. Protection Against DDoS
No single method
Attackers make use of innocent victims by secretly installing software on their machines
have machines continuously monitor their state by checking files for pollution!!
Continuously monitor network traffic
Concentrate on ingress routers
too late as the network will probably already be unreachable for regular traffic

18. Conclusion
Access control for distributed systems still have loopholes that needed to be addressed
New attacks continue to emerge on Distributed systems
Cloud Environment has a great demand for secure access control system*
*Li, Hongjiao, et al. "A Survey of Extended Role-Based Access Control in Cloud Computing." Proceedings of the 4th International Conference on Computer Engineering and Networks. Springer International Publishing, 2015.

19. Referances
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