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Botnets : Attacks and Defense

Botnets : Attacks and Defense. by Sammie Bush and Lance Pendergrass. Basic Definitions. Botnet - network of compromised machines that can be remotely controlled by an attacker Bot , “ zombie ” - an unwillingly infected host

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Botnets : Attacks and Defense

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  1. Botnets: Attacks and Defense by Sammie Bush and Lance Pendergrass

  2. Basic Definitions • Botnet - network of compromised machines that can be remotely controlled by an attacker • Bot, “zombie” - an unwillingly infected host • Command & Control (C&C) - some channel or structure acting as a handler in relaying commands and updates to the bots • Botmaster, Bot-herder - person(s) anonymously controlling the botnet via C&C

  3. Motivation • Notoriety versus Long-Term Control • Survivability • DDoS / Extortion • Spam • Identity Theft • keylogging • traffic captures • ClickFraud / PollManipulation • BitcoinMining–involuntarycloudcomputing • Distributed Storage – warez, malware • Search Engine Optimization (SEO) poisoning • BlackmarketServicesfor Rent

  4. C&C relaying instructions to launch DDoS attack

  5. Typical Lifecycle • Creation / Testing • Infection • Software Vulnerability • Drive-By Download • Trojan Horse (email attachment, pirated software) • Usually followed by rootkit, infecting system restore • Rallying – contacting C&C • Potential Propagation • Waiting • Executing Instructions

  6. IRC Botnets • Historically most common • Centralized topology • Support large number of connections • Traffic not as common, easily blocked • Server often hosted in public network such as Efnet, Undernet

  7. HTTP Botnets • Typically allowed through firewalls • Server easily hidden in plain view • Https support trivial, difficult to inspect • Doesn’t scale as well, easy to overload server • Covert channels: DNS, ICMP, SSL, RSS feed, IM

  8. HTTP communications channel with C&C

  9. Decentralized P2P Botnets • Lack single point of failure, no centralized C&C • Often seeded with initial nodes to contact • Download list or learn current peers • Common for nodes to relay/proxy traffic • Typically make use of existing P2P protocols: BitTorrent, eDonkey/Overnet, Kademlia DHT

  10. Evasion Techniques • Multiple Failover C&C servers • Dynamic DNS • Domain Generation Algorithms (DGA) • Fast-Flux / Internal Round-Robin Proxies • Protocol / IPv6 tunneling • Botmaster concealment: SOCKS, TOR, BNC’s • Polymorphism / Obfuscation

  11. Defense • OS / Software Updates • Antivirus / IDS Signatures • Network Baselines / Anomaly Detection • Firewall Rules • Domain seizure / Contact ISP Hosting C&C • Agent masquerading / Honeypots • MitM Attacks against HTTPS communication • Sinkholing – analyzing DGA, capturing C&C • Reverse Engineering – IDA Pro, OllyDbg, Wireshark • BotmasterTraceback

  12. Select History • Agobot (2002 ) – first to use modular design, staged payloads • Sinowal (2005) – 1.2 million bots, rootkit/MBR, banking credential thief • Zeus (2007) – targets banking info, estimated $12.5mil loss, RC4/XOR encoded traffic, source code leaked in 2011 leading to many variants, custom kits for sale in blackhat forums • Storm (2007) – estimated at 1-5mil bots, p2p topology, made use of Fast-Flux technique, IPS rivaling many supercomputers, reputation for launching DDoSdefensive measures against researchers • SpyEye (2009) – predecessor / competitor to Zeus, Zeus removal, financial MitM attacks, credential theft • TDL-4 / Alureon (2011) – 4.5mil bots, MBR rootkit, encrypted p2p communication, removes rival malware, variant implements malicious DHCP/DNS server, used for spamming, DDoS, proxies

  13. DIY HTTP Based Botnet Kit (1)

  14. DIY HTTP Based Botnet Kit (1)

  15. Cythosia Botnet Kit, AJAX Webpanel, SOCKSv5 Proxy, DDoS

  16. Cythosia cont.

  17. Skynet C&C (Zues variant, 2013) – generated over $1mil in Bitcoins

  18. Sources • Network and System Security, 2ed [2013] – John Vacca http://www.amazon.com/Network-System-Security-Second-Vacca/dp/012416689X/ • http://www.fortinet.com/sites/default/files/whitepapers/Anatomy-of-a-Botnet-WP.pdf • https://www.sans.org/reading-room/whitepapers/malicious/byob-build-botnet-33729 • http://threatpost.com/peer-to-peer-botnets-resilient-to-takedown-attempts/100851

  19. Sources • http://countermeasures.trendmicro.eu/history-of-the-botnet-white-paper/ • http://threatpost.com/coming-better-ways-count-and-counter-botnets-050212/76516 • http://arstechnica.com/security/2013/04/a-beginners-guide-to-building-botnets-with-little-assembly-required/ • http://www.wired.com/wiredsmallbizprogram/howto-28.html • https://community.rapid7.com/community/infosec/blog/2012/12/06/skynet-a-tor-powered-botnet-straight-from-reddit

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