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DDoS attacks landscape Marek Majkowski @majek04

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Reverse proxy 3 Eyeball Reverse proxy Origin server • Optimizations • Caching • Security • DDoS protection

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5 Denial of service

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Goal? 8

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Unavailability 16

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17 Break the internet

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Internet was built as a trusted environment 18

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19 https://www.fbi.gov/wanted/cyber

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Five case studies 21

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Amplification is largest 22

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24 Two things needed: - IP spoofing - vulnerable protocol

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25 IP Spoofing

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26 5.6.7.8 8.8.8.8 IP Spoofing

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27 Enables impersonation Real 8.8.8.8 Destination 5.6.7.8 Spoofed 8.8.8.8

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28 Spoofed? (source: DaPuglet)

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bulletproof hostig 29

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30 Find a protocol to abuse • DNS • NTP • SSDP

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31 UDP Server UDP Client request response

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32 Attacker Target UDP Server request response

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33 Attacker Target UDP Server request response 10 bytes 100 bytes

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34 Attacker Target UDP Servers requests responses

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Memcached (1.7 Tbps) February 2018 36

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Memcached does UDP? 37

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Cleanup was well underway • Digital Ocean • Linode • OVH • Amazon 43

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Memcached today 44

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Direct SYN flood 46

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47 Target Server Attacker 500 Gbps Direct SYN flood

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Is it a day job? 59

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60 Direct attack today

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Imaginary attacks 61

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Application attacks are small 66

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67 We know who attacks us! (source: the internet)

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IoT - Cameras 70

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76 GET /en HTTP/1.1 User-Agent: Cookie: Host: example.com Connection: close Content-Length: 800000 a[]=&b[]=&a[]=&b[]=&a[]=&b[]=&a[]=&b[]=&a[]=&b[]=&a[]=&b[]=...

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79 • Mirai - cameras • TR-069/TR-064 Deutsche Telefon - CPE • Reaper - D-Link, Netgear, and AVTech • VPNFilter - routers and NAS Evolution of IoT botnets

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WireX - Android malware 80

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82 User-Agent: jigpuzbcomkenhvladtwysqfxr User-Agent: yudjmikcvzoqwsbflghtxpanre User-Agent: mckvhaflwzbderiysoguxnqtpj User-Agent: deogjvtynmcxzwfsbahirukqpl User-Agent: fdmjczoeyarnuqkbgtlivsxhwp User-Agent: yczfxlrenuqtwmavhojpigkdsb User-Agent: dnlseufokcgvmajqzpbtrwyxih

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88 function attack(String target, String userAgent, String referer) { HashMap WebViewHeaders = new HashMap(); WebViewHeaders->put(“Referer”,referer); WebViewHeaders->put(“X-Requested-With”,””); WebView[] AttackerViews = new WebView[100]; for (int i=0; iclearHistory(); AttackerViews[i]->clearFormData(); AttackerViews[i]->clearCache(true); WebViewSettings AWVS = AttackerViews[i]->getSettings() AttackWebViewSettings->setJavaScriptEnabled(true); AttackWebViewSettings->setUserAgentString(userAgent); AttackWebViewSettings->setCacheMode(LOAD_NO_CACHE); this->deleteDatabase(“webview.db”); this->deleteDatabase(“webviewCache.db”); AttackerViews[i]->loadUrl(target,WebViewHeaders); } } }

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More.... 90

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Mobile ads 91

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95 function post_send() { var xmlHttp=c_xmlHttp(); xmlHttp.open("POST",t_url8,true); xmlHttp.setRequestHeader("Content-Type", ""); xmlHttp.send(t_postdata); r_send(); } function r_send() { setTimeout("post_send()", 50); }

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Hard to mitigate 96

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Porcupine 97

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Porcupine: Profile • Junk payload L7 attacks • Pretty large - 1M rps, 200k IP's/h • Brasil, Algeria, Tunisia, Ukraine • Attacker: . • Infection: . 103

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Cloudflare 105

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106 Anycast Architecture

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107 192.0.2.0/24 Internet Los Angeles 192.0.2.0/24 London 192.0.2.0/24 Amsterdam 192.0.2.0/24 Moscow 192.0.2.0/24 San Jose 192.0.2.0/24 New York

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Divide and conquer • DNS • splits traffic against multiple IPs • Anycast • splits traffic globally • ECMP • splits traffic within datacenter • Tuned network card • splits traffic across CPUs 110

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111 Automatic Mitigations

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112 iptables -A INPUT \ --dst 1.2.3.4 \ -p udp --dport 53 \ -m bpf --bytecode "14,0 0 0 20,177 0 0 0,12 0 0 0,7 0 0 0,64 0 0 0,21 0 7 124090465,64 0 0 4,21 0 5 1836084325,64 0 0 8,21 0 3 56848237,80 0 0 12,21 0 1 0,6 0 0 1,6 0 0 0" \ -j DROP

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113 ldx 4*([14]&0xf) ld #34 add x tax lb_0: ldb [x + 0] add x add #1 tax ld [x + 0] jneq #0x07657861, lb_1 ld [x + 4] jneq #0x6d706c65, lb_1 ld [x + 8] jneq #0x03636f6d, lb_1 ldb [x + 12] jneq #0x00, lb_1 ret #1 lb_1: ret #0

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Iptables for application attacks • Conntrack Connlimit - limit concurrent connections • Hashlimits - limit rate of connections • Rate limit SYN packets per IP • Ipset - blacklisting of IP addresses • Manual blacklisting - feed IP blacklist from HTTP server logs • Supports subnets, timeouts • Automatic blacklisting hashlimits 114

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115 Internet Router NIC Kernel App iptables fingerprints XDP

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Thanks! • Architected for DDoS • Iptables are great • Reduce DNS TTL • Keep your IoT firmware in check • Don't install random APKs • Use 1.1.1.1 resolver :) 116 marek@cloudflare.com @majek04