1. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com1 | IPv6 and Spam 2009 MIT Spam Conference Peter Kosik, Patrik Ostrihon and Reza Rajabiun reza@comdomsoft.com

2. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com2 | Spam Economics End user and network costs of spam ITU (2008): Economic implications of malware and spam (bandwidth, processing, storage, annoyance, etc.) This paper: A more pernicious problem Spam also limits incentives to adopt efficiency enhancing technologies and standards  Specifically: Constrains the diffusion of IPv6 at the AS level  Implications: Technological sclerosis and network fragmentation  Why? Alters the relative capacities of attackers/defenders

3. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com3 | Relevance (Source: Amsterdam Internet Exchange)

4. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com4 | IPv6 Economics Demand:  Address space exhaustion (128 v. 32 bit design)  Network Address Translation leads to fragmentation (big problem in developing countries in particular) Supply:  Very limited even in countries with more to gain from a switch  Less than 1% in all countries (Google, 2008),  Leaders in deploying IPv6: Entities with need for large space: DOD, cable operators (IPv6 lite)

5. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com5 | Allocation of address space (Source: CAIDA)

6. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com6 | Emerging IPv6 network (Source: Dolphin Network Discovery System, Key State Laboratory)

7. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com7 | IPv6 Diffusion Not an end user problem: End users usually do not make choices about IP  Technology bundling: Transition between Windows XP to Vista required to stimulate ISP investment in IPv6 specific infrastructure.  Vista necessary, but not sufficient for IPv6 diffusion  Why? Positive network externalities: Multiple equilibrium problem in the level of diffusion  Central variable: Decisions by Autonomous Systems/upstream operators

8. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com8 | Technological decisions Traditional diffusion model S-curve: A small proportion of population adopt first, then rate increases --> Deterministic Elmore et al. (2008): Significant resistance to IPv6 adoption. Possible solutions:  Public subsidies  Partial mandates  Technological bundling

9. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com9 | Technological decisions AS decision interdependence Game theoretical perspective --> Stochastic process In the presence of positive network externalities/strategic complementarities:  Decisions by sellers/firms reinforce each other  Possibility of a stable (inefficient) Nash equilibrium with persistent low penetration  Possibility of rapid shifts from sub-optimal Nash to Pareto efficient states

10. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com10 | Decision processes AS IPv6 decisions 1) Delay/not delay investment 2) Full /IPv6 lite General model of diffusion of binary decisions in network games. Jackson and Yariv (2007): In the presence of strategic complementarities, Bayesian Nash equilibrium exists and conveyance behavior monotone (up/down) Let x – Prob. of random network i adopting IPv6 Let d – Degree distribution for network i (links)

11. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com11 | Edge rewiring and stability of equilibrium Diffusion

12. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com12 | Adopt only if c i ≤ v(d i, x) Three basic decision processes: When an AS only cares about the average play of her neighbors, and network structure does not matter: v (d,x) = u(x) When a network’s individual payoff to IPv6 is a function of expected number of neighbors adopting IPv6: v (d,x) = u(dx) When v(d,x) is a step function, so that the decision to adopt IPv6 takes place only if x lies above a specific subjective threshold.

13. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com13 | Interpretation If degree distribution matters: Hypothesis: Decisions by networks with the largest number of linkages will determine the equilibrium level of diffusion. Xiao et al. (2009): Empirical analysis of emerging topology  Degree distribution of IPv6 ASs follows power law distribution  Power law exponent is around 1.2 (much lower than Ipv4, at approx. 2.2)  IPv6 connectivity less uniformly distributed --> Big networks have to move first

14. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com14 | IPv6 and Complexity (Source: Dolphin NDS)

15. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com15 | Spam and Technological Decisions  Kimakova and Rajabiun (2008) War of attrition: More spam with more antispam (another example of strategic complementarities)  Kanich et al. (2008): Very low conversion rates (in both responses to mass advertisements and infections)  O'Donnell (2008): Strong incentives to switch to new channels for extracting value from targets (OS vulnerabilities, other messaging applications) Key question: How does IPv6 change relative capacities of attackers and defenders?

16. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com16 | IPv6 angles of attack Three specific channels:  OS/application specific vulnerabilities – usually patched quickly by vendors (See: US-CERT database)  Large address space makes it easier to hide – Erosion of value of sender information » Accuracy: BGP Spectrum Agility techniques and one shot mailings » False positives: Reputation hijacking  Auto configuration and neighbor discovery

17. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com17 | IPv6 and Spam IP evolution: Davis et al. (2006): IPv6 may help with the spam problem, if: 1) A property regime could be created to make reputation of senders more credible  Would lead to more reputation hijacking and not realistic 2) The near infinite address space made it more difficult for spammers to probe the network for vulnerabilities

18. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com18 | Downstream admin. Passive Decisions MS Exchange 2007 Antispam and Antivirus Functionality: “ …strongly recommend against configuring Receive connectors to accept anonymous connections from unknown IPv6 addresses. If your organization must receive mail from senders who use IPv6 addresses, create a dedicated Receive connector that restricts the remote IP addresses to the specific IPv6 addresses that those senders use. If you configure a Receive connector to accept anonymous connections from unknown IPv6 addresses, the amount of spam that enters your organization is likely to increase.”

19. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com19 | (Semi) Autonomous Systems Active Decisions ISPs with large d's: their IPv6 decisions matter most to diffusion Problem: Reliant on DNSRBLs and reputation based filtering (50- 60% of the spam/total load) If IPv6 large address space erodes reputation, then 1) Forgone investments in spam defenses 2) Increases in infrastructure costs since reputation is perceived to be cheaper than content analysis (processing, storage, etc.)

20. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com20 | Rational expectations and transition to IPv6  Port scanning and information gathering: Bellovin et al. (2006): Using a two stage search process IPv6 neighborhood discovery logs can be used to collect necessary info. In addition to active scanning techniques, ASs expect that in an IPv6 world:  Target discovery and worm propagation: Relatively easy since computers in IPv6 space will likely live near each other (given adjacent addresses by ISPs). Much like agglomeration of people in cities.

21. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com21 | Spamming in IPv6  Shifting targeting paradigm Most computers in the world already protected by NATs from active and passive scanning Result: Spammers devise techniques that let their prey come to them!  Place malicious code on WWW servers.  Infiltrate routers of big ISPs.  Use BGP to redirect traffic.

22. © ComDom Software | www.comdomsoft.com | info@comdomsoft.com22 | Implications and Discussion  IPv6 lite implementation will not help address the strategic decisions that influence aggregate diffusion rates (edges using NATs and IPv4)  IPv6 diffusion requires complementary changes in technologies for spam processing  Stronger sender authentication (DKIM, etc.), or Accountable Internet Protocol (AIP) as in Andersen et al. (2008).  Increased emphasis on content analysis and statistical filters.