Wireless Network Security Spring 2011

Transcription

1 Wireless Network Security Spring 2011 Patrick Tague Mar 22, 2011 Class #19 Cross-layer attacks and defenses

2 Announcements Homework #3 is due March 24 Exam in class March 31

3 Agenda Cross-layer attacks and defenses Layering and cross-layer design How attackers plan and execute How defenders design

4 Layering and Cross-Layer Design

5 Layering Networks are complex Layering simplifies network design Layered model: Layer 3 Layer 2 Layer 1 Lower layer provides a service to higher layer Higher layer doesn t care how service is implemented: transparency

6 Layered Operation Node A Application Layer Transport Layer Network Layer Link Layer Physical Layer Router Network Layer Link Layer Physical Layer Node B Application Layer Transport Layer Network Layer Link Layer Physical Layer Physical Medium

7 Pros/Cons of Layered Design Layering Pros Simplified design Layer transparency Modularity Layering Cons Hidden information can help performance Loss of context in wireless networks

8 Layering in Wireless Layering impacts wireless protocols Hiding physical layer upper layers see wired Cannot leverage advantages of wireless Layering is not appropriate for many wireless systems Wired Wireless Application Transport Network Link Physical

9 Broadcast B d AB E C D A F Broadcast Advantage Sender A transmitting to receiver B can reach other nodes at distance less than d AB for free

10 Cross-Layer Design Cross-layer design Sharing info helps performance Transparency lost Design is more challenging Application Transport Network Link Physical

11 Cross-Layer (R)Evolution Cross-layer evolution Incorporate cross-layer information sharing into a layered architecture Layering properties are minimally violated Protocols are still pretty widely usable Cross-layer revolution Design new architecture from the ground up Protocols are highly customized, narrowly usable Application Transport Network Link Physical

12 Ex: Broadcast Routing Minimum energy broadcast routing Design a routing protocol for node A to send a message to all other nodes with the minimum total energy expenditure G B C D A F E

13 Ex: Localization Allow a node A to estimate its location (x A,y A ) using messages and measurements from other nodes A needs to receive messages from B and C A uses physical properties of received signal to measure relative geometry Reported locations and measurements can be used to estimate (x A,y A ) B is at (x B,y B ) C is at (x C,y C ) B A C d AB δ B (x A,y A )? d AC δ C

14 How Attackers Plan and Execute

15 Layered Attacks Layering simplifies attack planning Layered attack model: Layer 3 Layer 2 Attackers can similarly rely on layered transparency, relying on generic services provided by other layers Layer 1

16 Pros/Cons of Attack Layering Layered Attack Pros Simplified planning and execution of attacks Transparency Layered Attack Cons Hidden information could make attack more effective, efficient, etc. Loss of context Modularity

17 Cross-Layer Attacks Cross-layer attacks Sharing information across protocol layers to improve attack performance For any definition of performance Planning and optimizing attacks may be much more challenging Application Transport Network Link Physical

18 Example Collaborating jammers with information about network flow topology and traffic rates can load-balance Source s Dest d Jammer load-balancing

19 Survey More Examples Thursday's survey topic is Cross-layer attack strategies Additional reading If you'd like more examples, I'll give you some references

20 How Defenders Design

21 Layered Defenses for Layered Attacks Layered Attack vs. Layered Defense This is what I consider classical network security Layer n protocols protect against layer n vulnerabilities Little/no protection from cascading attack impacts

22 Layered Defenses for Cross-Layer Attacks Cross-Layer Attack vs. Layered Defense Advanced attacks developed against classical network defenses Most likely, the attackers are going to win At a cost, of course

23 Cross-Layer Defenses for Layered Attacks Layered Attack vs. Cross-Layer Defense Classical attacks applied to advanced networking If well designed, defenses should come out ahead Again, at a cost

24 Cross-Layer Defenses for Cross-Layer Attacks Advanced Attack vs. Advanced Defense Most interesting case where there isn't much work yet How advanced do defenses need to be to keep up with the advanced attacks? Hard question... Can we come up with a general framework to allow a defender to learn and adapt to what it sees? Attacker can do the same thing now we have a game

25 Comparison Layered Attack Cross-Layer Attack Layered Defense Attack elements can target specific protocol performance Attacks are easy to plan, but probably sub-optimal Attacker may be smarter than the network under attack Attack has fairly low cost to optimize, but likely to succeed Cross-Layer Defense Detection of attacks is more likely due to cross-layer impacts Defense is more costly, but likely to succeed More difficult to characterize, optimize, predict, plan, Attack and defense are more costly Red vs. Blue games

26 Next time... Mar 24: Survey cross-layer attacks Mar 29: Survey data aggregation in WSN Mar 31: Exam