secure operating stuff lesson “like” 7 (a): virtualization
TRANSCRIPT
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Secure Operating StuffLesson “like” 7 (a): Virtualization
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Virtualization Because of the hype around “the cloud”,
virtualization has become pretty big news However, virtualization is something we
really need to understand if we want to reason about host and OS :P security
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What is Virtualization? Type 1 Hypervisor
“native”, “bare metal” Type 2 Hypervisor
“hosted”
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Paravirtualization Instead of modifying all the IO to run through
the Hypervisor, we can modify the hosted OS to use specific calls for IO Think of this as collaborative virtualization, in
essence (hosted OS “collaborates” to take part in the illusion)
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How? There are really only three different routes to
machine virtualization… How would you do it? What problems do we need to think about?
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Hardware Assistance Intel and AMD have extended their
instruction set to provide hardware support for virtualization The Intel VT-I and VT-x instruction sets are
powerful, and create a very capable platform I have no comment on the AMD instructions, as I
am less familiar with them
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Possible Threat: SubVirt Theoretically (and in practice) you could
make malware which threw the entire host OS into a VM Benefits? Disadvantages?
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Detecting a VM Rootkit? One basic tenet…
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The Presence of Covert Channels What is a covert channel?
Lampson: a channel “not intended for information transfer at all, such as the service program’s effect on system load”
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Five Concerns from Bratus et al.1. Weaknesses in remote management
2. Increase in management cost (the VM and the host)
3. Creeping Guest to Host APIs
4. Information Flow Policy (see “Virtual Machines, Virtual Security”)
5. Conflation of two issues – the provider and the monitor…
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Virtual Machine, Virtual Security? This is really a nice little article that forces
you to think about isolation – if we split everything up, we need to make holes to use the systems…
How many OS vulns really relied on exploits of the privilege system? How many relied on incorrect privileges?
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Why do we think we can do this?
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With that said… Virtualization Can Help
Malware Analysis Rollback/trusted monitor “Disposable” computing
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But also… Virtualization Can Hurt
Rootkits Covert Channels Escape from the VMM
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To Do If you’re interested (will help but is not
required reading – good reference) read “Intel Virtualization Technology: Hardware Support for Efficient Processor Virtualization”
For the exam, must read “VM-based security overkill: a lament for applied systems security research” and (the very short) “Virtual Machines, Virtual Security”