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Emulab Security

Emulab Security. Current Security Model. Threat model: No malicious authenticated users, Bad Guys are all “outside” Protect against accidents on the “inside” Provide prudent protection from the “outside” We are a research facility, must balance security and openness

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Emulab Security

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  1. Emulab Security

  2. Current Security Model • Threat model: No malicious authenticated users, Bad Guys are all “outside” • Protect against accidents on the “inside” • Provide prudent protection from the “outside” • We are a research facility, must balance security and openness • Cannot close all network ports • Cannot (always) take away root privilege

  3. Current Security Model(cont.) • We can observe basic security hygiene • No cleartext passwords • Firewall from the outside world • Restrict access to critical infrastructure services • Happily, experiment isolation and security are synergistic • Experiment private VLANs • Reloading disks between experiments

  4. Local node security • Protect against accidental breaches of confidentiality, integrity, and availability • Malicious violations handled through non-technical means

  5. Wide-area node security • Not under our physical or administrative control • Limited control over who accesses a node • Node may or may not be firewalled • Not just us who looks bad if there is an “incident” • Bottom line: must be more cautious! • Use authenticated network protocols • Restrict privilege of Emulab users on nodes

  6. User Security • Potential new users must be part of an informal “chain of trust” • New users verified with a key in e-mail • All interaction with the testbed done using secure protocols • Projects are separated from each other • Users allowed to access only one server, critical services run on another

  7. Node Security • Physical nodes are not shared between experiments • Use a shared filesystem (NFS), but export only appropriate directories from the server • Node disks are reloaded and nodes rebooted when released from an experiment

  8. Network Security • Use VLANs on the experimental network to enforce isolation • Control network divided into 5 subnets with firewalling in between • “External” VLAN for link to the outside world • “Device” VLAN for SNMP devices • “Private” VLAN for boss node and critical servers • “Public” VLAN for user-accessible nodes • “Node” VLAN for the nodes

  9. Network Security(cont.) • MAC security on node control net • Nodes cannot spoof other active MAC addresses • Basic egress/ingress filtering • Nodes cannot spoof external IP addresses

  10. Emulab SecurityThe Future

  11. Flaws: current threat model • Assumption: “Only good, though sometimes careless, people on the inside” • Node control net • Interface is visible, and desirable, to applications • Shared by all nodes in all experiments • Vulnerable services on the private VLAN • Always-a-popular-target web server on the same net/host as central DB, power controllers, switches

  12. Flaws: relaxed threat model • Assumption: “Anything goes” • Node control net • Spoofing/interfering with infrastructure services • Vulnerable services on the private VLAN • Direct attacks on unauthenticated services: TFTP, tmcc, event system • Cracking user logins on ops node • Exposes all user files as ops is FS server • Exposes user ssh keys, can get to any node

  13. More exotic threats • Switch DOSin' • Directed attacks on the switch infrastructure • Could affect switching performance • Could also prevent reconfiguration of a switch (this has happened to us!) • BIOS whackin' • Attempt to corrupt or infect the BIOS • Stash trojans in non-volatile memory • Can it be done?

  14. Fixing the current flaws • Secure the control net • Per-experiment VLANs ala the experimental net • Address vulnerable services • Get web server off of private net • Design narrow, proxy interfaces to critical services • Eliminate local shared file storage or replace NFS • Eliminate local server logins • Secure the hardware • Configure a small pool of directly connected nodes • Ensure BIOS modification requires manual labor • PCs with Trusted Platform Modules?

  15. Worms and Virii:dealing with the Really Bad S**t • Need to protect, not just us, but the Internet • Cannot just fix flaws we know about, must assume there are worse ones we don't know • Need support for Microsoft Windows • Cannot have chaos and destruction without it! • What do we do?

  16. Emulab experiment today

  17. Solution #1: firewalls • Create a virtual control net for an experiment and interpose a gateway “firewall node” • Could be implicitly or explicitly configured • Allows external access and monitoring of an experiment • Flexible, but still vulnerable

  18. Firewalled Experiment

  19. Solution #2: “Emulab Unplugged” • Run an experiment in a completely disconnected fashion • Regular control net is used to configure the experiment, and is then disabled • Only access via serial line • Might not work so hot for Windows • Watch out for escape sequence attacks!

  20. Isolated Experiment

  21. Monitoring and control • How do we observee and control the behavior of hard cases? • Switch statistics (if using a switch) • Interposed “monitor nodes” • Applications running on the nodes (how far can you trust them?) • Postmortem analysis • Remote nodes into MFS, examine filesystems

  22. Limitations of our environment • Using PCs as routers in topologies • Can they keep up? • Will they alter the behavior of the worm/virus? • Emulab-savvy worms • Is Emulab too easy to detect? • Do we need to disguise our environment?

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