1. Distributed Firewall Policy Validation by Kyle Wheeler

2. Outline 1. Introduction Justification Requirements 2. Design Approaches Architecture 3. Implementation Requirements Graphing Example Policy Example 4. Conclusions

3. Security is IMPORTANT Computer-based attacks are increasing Code Red: 2000 hosts/minute (2001) Slammer: 55 million scans/second (2003) Attacks are becoming more damaging CISCO’s IOS code stolen Valve’s HalfLife 2 code stolen Trend Micro says: $13 billion in 2001 $20 billion in 2002 $55 billion in 2003 (source)source

4. Security is HARD Firewalls Most popular security method Rules can and do become very complex Not only method, however Large networks have: Many different administrators Diverse software Security of large networks requires: Centralized control Uniform software No unified method of verifying security policy implementation For example, The University of Notre Dame network

5. Rules for the Solution Few Requirements Network-connectivity independent Mostly system-setup independent Cannot require root access Independent of firewall implementations Flexible Testing Out-of-order data collection (some support) Non-uniform distribution of testing nodes Define a testable security policy language

6. Analysis Approaches Static Vulnerability Analysis Splint Threat Modeling Regression Testing

7. Static Vulnerability Analysis The Good Avoids logical ambiguity Avoids common loopholes and mistakes Easy to understand The Bad Requires detailed knowledge of the implementation Implementation- specific Does not address system interactions

8. Threat Modeling The Good Models entire system Views system as an attacker would Determines vulnerability “surface” The Bad Requires full knowledge of all system details

9. Regression Testing The Good Does not need implementation- specific details Easy to understand The Bad Effectiveness is tied to the completeness of the policy Can miss some vulnerabilities

10. Data Collection Framework Hierarchical organization Handles complex networks Allows asynchronous operation Wizard Big picture management, handles policy testing setup Manager Organization, Coordination, Retrieval Prober Low-level testing, yes/no answers

11. Managers & Probers Good Features Subordinate Managers Commands can be any length Key Features Hierarchical Naming Maildir-like communication

12. Hierarchical Naming Names contain routing information Names are given or assigned Network must be laid out intelligently No auto-discovery Manually connectable Must be a root to the tree (base) Three kinds of sub-names base.m1.m1.p2.t1.t Example, slide 17, 12

13. Maildir-like Algorithm Benefits No locks: NFS safe No partial-files No new communication server to secure Two-step file creation Create in tmp, then move to new Need unique new name Use pid and random Could use more (inode#, for example) Waiting For Results Requires Polling

14. Given a complex network… Administrator’s Console Firewall Prober Manager Prober Manager Prober Manager Prober

15. … Handled Nicely Prober Manager Prober Manager Prober Manager Administrator’s Console Firewall

16. Or, More Realistically… 192.168.0.131 24.11.249.68 internet 129.74.152.6 129.74.152.2129.74.155.226 172.16.0.16172.16.0.17

17. ... Which Can be Organized 192.168.0.130 Wizard & Manager base 192.168.0.132 Prober base.p1 192.168.0.131 Prober base.p2 129.74.152.2 Prober base.m1.p2 172.16.0.17 Prober base.m1.m1.p2 172.16.0.16 Prober base.m1.m1.p1 129.74.155.226 Manager - base.m1 Prober - base.p3 129.7.152.6 Manager - base.m1.m1 Prober - base.m1.p1 24.11.249.68 Prober base.p4

18. The Implementation Requirements: ttcp installed in PATH Binary connection testing bash available, in PATH Written in bash SSH access, without password Security issue Impact can be reduced with careful administration Graphing with Graphviz

19. Raw Manager Capability Hosts, fully connected: wopr.memoryhole.net iss.cse.nd.edu salinan.cse.nd.edu itisfast.cse.nd.edu Legend: Black line = confirmed connection Dotted line = one side reported connection Red line = one side reported, one side denied

20. The Wizard Interchangeable element Interprets policy language Generates and spawns tests At least three per assertion Otherwise 50% of all possible Interprets results of tests Must have control of “base” Manager

21. Example Policy network iss 172.16.0.0 255.255.0.0 network nd 127.74.0.0 255.255.0.0 network brk 192.168.0.0 255.255.0.0 brk -> nd brk -> iss via 129.74.152.6 nd -> brk via 24.11.249.168 nd -> iss via 129.74.152.6 iss -X nd iss -X brk 16

22. Conclusions Design is feasible Implementation works as expected Being generic is hard Future Work Investigate long-running “continuous” testing Policy language needs further flexibility Speed of testing

23. Any Questions?