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Owning nx os-sec-t_2010

Slides presented at SEC-T September 10th, 2010.

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Owning nx os-sec-t_2010

  1. 1. Owning the data centre, Cisco NX-OS<br />George Hedfors<br />Working for Cybercom Sweden East AB(http://www.cybercomgroup.com)<br />12 years as IT- and information security consultant<br />Previously worked for iX Security, Defcom, NetSec, n.runs and Pinion<br />Contact george.hedfors@cybercomgroup.com<br />Web page http://george.hedfors.com<br />2010-08-10<br />SEC-T 2010<br />1<br />
  2. 2. Short intro to Cisco NX-OS<br />History of research<br />Overview of underlying Linux<br />Disclosure of vulnerabilities<br />Undocumented CLi commands<br />Command line interface escape<br />Layer 2 attack<br />Undocumented user account<br />2ndCLi escape (delayed)<br />FAQ<br />Topics<br />2010-08-10<br />SEC-T<br />2<br />
  3. 3. Based on MontaVista (http://www.mvista.com)embedded Linux with kernel 2.6.10<br />VDC Virtualization, Virtual Device Context<br />What is NX-OS?<br />2010-08-10<br />SEC-T 2010<br />3<br />Nexus 4000 (for IBM BladeCenter)<br />Nexus 5000<br />Nexus 7000<br />MDS 9500 FC Directors<br />MDS 9222i FC Switch<br />MDS 9100 FC Switches<br />
  4. 4. Accidentally made a Cisco-7020 fall over due to an 9 years old denial of service attack<br />Was able to recover CORE dumps from the attack<br />Able to extract all files from the Cisco .bin installation package<br />Found a number of exploitable vulnerabilities<br />To do<br />Dig deeper into Cisco VDC/VRF security<br />What has been done<br />2010-08-10<br />SEC-T<br />4<br />
  5. 5. Typical environment<br />Banking/finance<br />Other large data centers<br />Impact<br />Full exposure of interconnected networks and VLAN’s<br />Possibility to eavesdrop and trafficmodification<br />Switch based rootkit installation?<br />Cisco 7000-series<br />2010-08-10<br />SEC-T<br />5<br />
  6. 6. Overview<br />2010-08-10<br />SEC-T<br />6<br />Linux<br />
  7. 7. Teh Linux<br />2010-08-10<br />SEC-T<br />7<br />root?!?<br />
  8. 8. DC3 Shell ‘the regular Cisco cli’<br />Configurations contain ‘hidden’ commands<br />Hidden commands<br />2010-08-10<br />SEC-T<br />8<br />
  9. 9. Escaping CLi<br />2010-08-10<br />SEC-T<br />9<br />
  10. 10. How could that happened?!<br />2010-08-10<br />SEC-T<br />10<br />What could possibly go wrong here?<br />/usr/bin/gdbserver<br />
  11. 11. Cisco Discovery Protocol (CDP)<br />2001, FX crafted the first CDP DoS attack<br />2010, the CDP attack was rediscovered in NX-OS<br />What about layer 2?<br />2010-08-10<br />SEC-T<br />11<br /><ul><li>CDP has become demonized and is now running under the ‘root’ user context</li></li></ul><li>The core dump<br />2010-08-10<br />SEC-T<br />12<br />
  12. 12. So, where ‘ftpuser’ come from?<br />Default user? Backdoor? Easter egg?<br />Recovered password ‘nbv123’<br />Undocumented user account<br />2010-08-10<br />SEC-T<br />13<br />
  13. 13. Searching for ‘nbv123’<br />2010-08-10<br />SEC-T<br />14<br />
  14. 14. CSCti03724 – CLI escape in NX-OS using GDB<br />Workaround: None<br />Fixed in NX-OS 4.1(4)<br />CSCti04026 – Undocumented user available with default password on NX-OS system<br />Workaround: None<br />CSCtf08873 – CDP with long hostname crashes CDPD on N7k<br />Workaround: Disable CDP<br />CSCti85295 – NX-OS: SUDO privilege escalation<br />Workaround: None<br />Bug tracking<br />2010-08-10<br />SEC-T<br />15<br />
  15. 15. Special thanks to Juan-Manuel Gonzales, PSIRT Incident Manager <juagonza@cisco.com><br />Thanks<br />2010-08-10<br />SEC-T<br />16<br />
  16. 16. Questions?<br />Contact george.hedfors@cybercomgroup.com<br />FAQ<br />2010-08-10<br />SEC-T<br />17<br />

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