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DDoS Attacks
- 1. DDoS AttacksDDoS AttacksDDoS AttacksDDoS Attacks Vitor Jesus http://vitorjesus.com bcu@vitorjesus.com Birmingham 25-Aug-2017
- 2. for this online version, all figures and slides with copyright were removed
- 3. DoSDoSDoSDoS • a Denial-of-Service attack is one that prevents a [networked] function to work normally. • Overwhelming a server with traffic is DoS. • Remotely exhausting the available memory of an application is DoS. • It is distributed if there’s coordination of multiple parties to develop the attack.
- 4. DDoSDDoSDDoSDDoS DDoS unintended not meeting service demand not only for Internet applications unintended imperfect implementation or design of protocol intended
- 5. DDoSDDoSDDoSDDoS DDoS unintended not meeting service demand not only for Internet applications unintended imperfect implementation or design of protocol intended Cellular DoS
- 6. DDoSDDoSDDoSDDoS what is the Slashdot Effect?
- 7. DDoSDDoSDDoSDDoS DDoS unintended not meeting service demand not only for Internet applications unintended imperfect implementation or design of protocol intended Cellular DoS Slashdot effect
- 8. DDoSDDoSDDoSDDoS what is the oldest DDoS attack? (in the history of the Internet) (arguably) (not necessarily intended) (T&Cs apply)
- 9. DDoSDDoSDDoSDDoS what is the oldest DDoS attack? figures removed – OSPF flooding processes
- 10. DDoSDDoSDDoSDDoS DDoS unintended not meeting service demand not only for Internet applications unintended imperfect implementation or design of protocol intended Cellular DoS OSPF Slashdot effect
- 13. the scale of the problemthe scale of the problemthe scale of the problemthe scale of the problem (figures removed) DDoS peaks 2007: 20 Gbps 2010: 100 Gbps 2013: 300 Gbps 2016: ~1 Tbps 2017 TD: 100 Gbps
- 14. DDoS: it’s a businessDDoS: it’s a businessDDoS: it’s a businessDDoS: it’s a business • DDoS as a Service ran by two Israeli teenagers was shutdown • a 300sec DDoS attack with around 100Gbps could cost less than $10
- 15. ttttechniquesechniquesechniquesechniques 800Gbps: how can such a scale of bandwidth be created?
- 16. techniquestechniquestechniquestechniques step 1: find a widespread vulnerability in a protocol with good amplification (pps and size) step 2: find a way to reflect the traffic towards the victim step 3: (and/or) compromise hosts using another vulnerability – botnets Ballpark figures: • DNS amplification: 50% • NTP amplification: 30% • Chargen amplification: 10% • SSDP amplification: 10% • others: ~5%
- 17. aaaammmmpppplllliiiiffffiiiiccccaaaattttiiiioooonnnn ffffaaaaccccttttoooorrrr Christian Rossow, Amplification Hell: Revisiting Network Protocols for DDoS Abuse, NDSS ’14, 23-26 February 2014, San Diego, CA, USA
- 18. MiraiMiraiMiraiMirai bbbboooottttnnnneeeetttt•impact •it brought down Airbnb, Netflix, Amazon, Verizon, Twitter, PayPal, Spotify, etc. •it even impacted interdomain routing •then they attacked Brian Krebs •delivered peaks of 1 Tbps •Akamai (CDN) gave up. •Google offered Project Shield •Mirai compromised “things” •mostly IP cameras •source code available •traffic from 141 different countries •hundreds of thousands of devices •modus operandi •device tested for weak passwords •it connected to a C&C •multiple protocols: HTTP, GRE (VPN), plain TCP, DNS, plain UDP, … •20yo with minor contributions from others – arrested
- 19. a taxonomya taxonomya taxonomya taxonomy J Mirkovic, P Reiher, A Taxonomy of DDoS Attack and DDoS Defense Mechanisms, ACM Comp Comm Review, 2004
- 20. mitigationmitigationmitigationmitigation • Why is it even possible to do DDoS to this scale? Is the Internet not policed in some way? • for example, why can’t the operators just stop it? Everything is connected to an operator anyway and someone is paying the bill.
- 21. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation of legitimate and malicious traffic is not trivial • network and node resources will always be scarce • split intelligence vs resource • the Internet lacks in-built accountability • social: there’s often a void of legislation about DDoS; Authorities will investigate but that’s already after the fact.
- 22. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • Future Internet maybe? Not something most people would like to change.
- 23. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • perfect Security is impossible. That’s why we are all here in this room. • it combines Humans, Technologies, Standards, Practices, Regulations, Policies, Politics, Economics • Chargen: used in 11% attacks • mitigation of Mirai: • Secure Software Development practices – a semester on its own • Secure product delivery • Vendors should consider trading Features for Security • user awareness • better DNS and UPnP hardening; DNS with longer TTLs, discarding of stale records; redundant servers
- 24. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • many administratively independent parties • Governments/States, ISPs, private organisations, users, machines • DDoS can start in minutes – coordination times is challenging • Cyber Threat Intelligence is key: TAXII, STIX, CybOX • messaging (TXII) + representation of threats (STIX) + observables (CybOX) • https://www.us-cert.gov/Information-Sharing-Specifications-Cybersecurity • Jessica Steinberger, et al., Collaborative DDoS Defense using Flow-based Security Event Information, IEEE/IFIP NOMS, 2016 IETF DDoS Open Threat Signaling (DOTS), 2017 • François, Aib, Boutaba, FireCol: a collaborative protection network for the detection of flooding DDoS attacks, IEEE/ACM Trans. on Networking, v20, i6, Dec 2012 • distributed and collaborative IPS architecture on ISPs
- 25. aggregates of flows + context aggregates of flowsflowspackets mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation between legitimate and malicious traffic is not trivial • it builds on mathematical and statistical analysis • overall, math techniques are not quite cutting it • did not find a single paper on DDoS detection with context • context is a very complex topic • anyone wants to think about this? impossible unlikely possible likely very likely how, why, when, where, who
- 26. mmmmiiiittttiiiiggggaaaattttiiiioooonnnn ((((ddddeeeetttteeeeccccttttiiiioooonnnn,,,, 1111////2222)))) • Y. Xiang, Y. Lin, W.L. Lei, S.J. Huang, Detecting DDOS attack based on network self-similarity, IEE Communications Letters, Volume: 151, Issue: 3, June 2004 • Self-similarity is a statistical/fractal analysis. If it is high, zooming in/out (so playing with scales), will essentially not change the picture. • Lan Li, Gyungho Lee, DDoS Attack Detection and Wavelets, Springer, Telecommunication Systems, March 2005, Volume 28, Issue 3–4 • wavelets • Yu Chen, Kai Hwang, Collaborative detection and filtering of shrew DDoS attacks using spectral analysis, J of Parallel and Distributed Computing, Volume 66, Issue 9, September 2006 • shrew attacks – TCP-based. Just like in the cartoon.
- 27. mmmmiiiittttiiiiggggaaaattttiiiioooonnnn ((((ddddeeeetttteeeeccccttttiiiioooonnnn 2222////2222)))) • Shui Yu, Wanlei Zhou, Robin Doss, Weijia Jia, Traceback of DDoS Attacks Using Entropy Variations, IEEE Trans on Parallel and Distributed Systems, Volume: 22, Issue: 3, March 2011 • fingerprinting the traffic and tracing the signature back to the source • Yang Xiang, Ke Li, Wanlei Zhou, Low-Rate DDoS Attacks Detection and Traceback by Using New Information Metrics, IEEE Trans on Information Forensics and Security, Volume: 6, Issue: 2, June 2011 • low rate is harder to detect than a sharp pulse: DegDoS • S. Yu et al, Discriminating DDoS Attacks from Flash Crowds Using Flow Correlation Coefficient, IEEE Trans on Parallel and Distributed Systems, Volume: 23, Issue: 6, June 2012 • self-similarity of DDoS traffic is different than of flash crowds
- 28. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation of legitimate and malicious traffic is not trivial • network and node resources will always be scarce • because everything is scarce. This makes more sense, however, combined with the next.
- 29. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation of legitimate and malicious traffic is not trivial • network and node resources will always be scarce • split intelligence vs resource • interdomain, carrier-grade routers: built for packet switching speed • data centre application server: built for programmable functionality • this creates, however, the need for new types of elements: • L4+ firewalls, Load Balancers, Reverse Proxies, Web-Application Firewalls, CDNs, etc • their task is to be fast, resilient and simple (as possible) • cloud DDoS protection services: everything in the cloud
- 30. mmmmiiiittttiiiiggggaaaattttiiiioooonnnn ((((sssspppplllliiiitttt ffffeeeeaaaattttuuuurrrreeeessss)))) Cisco ASA F5 Barracuda nginx cloudflare incapsula
- 31. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation of legitimate and malicious traffic is not trivial • network and node resources will always be scarce • split intelligence vs resource • the Internet lacks in-built accountability • David G. Andersen, Hari Balakrishnan, Nick Feamster, Teemu Koponen, Daekyeong Moon, Scott Shenker, Accountable Internet Protocol (AIP), Sigcomm 2008 • very interesting paper. Utterly non-implementable nowadays. Future Internet maybe. • the source address is a public key; helps with DDoS, spoofing, routing trust • other approaches exist but one way or the other they requires disruptive changes to IP
- 32. mitigationmitigationmitigationmitigation –––– nnnnoooo eeeeaaaassssyyyy aaaannnnsssswwwweeeerrrr • end to end paradigm is still valid to a large extent • vulnerabilities, at different levels, will always exist • Internet security is highly interdependent • differentiation of legitimate and malicious traffic is not trivial • network and node resources will always be scarce • split intelligence vs resource • the Internet lacks in-built accountability • social: there’s often a void of legislation about DDoS; Authorities will investigate but that’s already after the fact. • helps as a deterrent but not much more • what public policies would help?
- 33. main takeawaysmain takeawaysmain takeawaysmain takeaways • the main enabling equation: • DDoS = amplifying vulnerabilities + reflecting traffic • DDoS is here to stay. • 20yo amateur software developer is able to bring down giants such as Amazon • There will always be a vulnerability to exploit. • it is a key concern, by far, of ISPs • Realtime defense progressed • detection techniques matured but only help so much • best solution so far: throw bandwidth back at it – horsepower + specialised nodes • It is a multidimensional problem • The Internet architecture does not help, deficient multiparty coordination, impossibility of detection assurances, limited accountability, there are economic incentives
- 34. ffffoooooooodddd ffffoooorrrr tttthhhhoooouuuugggghhhhtttt • a key problem is that sending a packet costs nothing • what if it costed a vestigial amount – so cheap for fair use but expensive for a DDoS • we do need an Accountable Internet • anybody sees where I am going? • imagine detection was perfect and just about 5min before it started • can we blackhole this traffic at the interdomain level? • inter-ISP coordination is the key • what would be an effective, and reasonable public policy? • hint 1: DfT guidance on Security for connected cars, August-2017 • hint 2: US Internet of Things Cybersecurity Improvement Act of 2017
- 35. further readingfurther readingfurther readingfurther reading • Alberto Compagno, Mauro Conti, Paolo Gasti, Gene Tsudik, Poseidon: Mitigating interest flooding DDoS attacks in Named Data Networking, 38th IEEE Local Computer Networks (LCN) Conf, 2013 • Rodrigo Braga, Edjard Mota, Alexandre Passito, Lightweight DDoS flooding attack detection using NOX/OpenFlow, 35th IEEE Local Computer Networks (LCN) Conf, 2010 • Bing Wang, Yao Zheng, Wenjing Lou, Y. Thomas Hou, DDoS attack protection in the era of cloud computing and Software-Defined Networking, Computer Networks (ComNet), Volume 81, 22 April 2015 • Qiao Yan, F. Richard Yu, Qingxiang Gong, Jianqiang Li, Software-Defined Networking (SDN) and Distributed Denial of Service (DDoS) Attacks in Cloud Computing Environments: A Survey, Some Research Issues, and Challenges, IEEE Communications Surveys & Tutorials, V 18, I 1, 1Q 2016 • very recommended and easy to read
- 36. Thank you.