tssci security

Hardware VM security: past and present

Marcin and I were talking a bit about mainframe security today. I recalled how fantastic mainframes were while he had his hands in the trenches. Yes, I know that IBM renamed MVS to z/OS (as well as other things) years ago. However, the concepts remain the same: TSO, ISPF, and JCL are still there.

I tried to explain some of the differences between z/VM and z/OS. z/VM is based on VM/CMS, which ran an antiquated version of hardware virtualization concepts that we find in modern technology such as Xen. I also pointed Marcin to the Wikipedia entry for RACF, where we checked out and discussed all the links. Recently, I had also read Mainframe Basics for Security Professionals, so you can check it out if you want more information.

As we got deeper into the conversation, we talked less and less about mainframes and more and more about Xen. I related concepts of clustering from the Big Blue days of IBM, which ran AIX on SP2 clusters. What Xen and new-age hardware virtualization packages are lacking is not only security concepts, but also general improvements and refinement of technique.

The whole point of running multiple OSes on a single machine escapes most people. They mostly want it so that they can run Mac OS X and Windows on the same laptop. That's the opposite of what this technology is meant to do. It's for big servers with lots of processors and memory. It's intended to be able to migrate, restore, route-around availability issues, and increase performance.

That's correct: increase performance while also moving an OS between physical machines. Late at night, an entire mainframe-sized machine or two can be shutdown for maintenance and to save money on power -- while another mainframe-sized machine picks up that work until early in the morning.

Some people say, "well if this computer is sitting here only running one task on CPU for 4 hours a day at 90%, then we can just run SETI@home the rest of the time it's idling at 10%". This is exactly the kind of attitude that caused the Dot-Com era way of thinking. The real goal is to move services off that machine when it's not using them, and safely carry them out elsewhere.

Speaking of the laptop, think of Xen save/restore/migrate more like your laptop's hibernate feature. When it comes up again, you're back in business. Xen migrate makes moving an OS between machines "instant business". The primary extra difficulty system administrators and IT people have with understanding Xen migration is that it requires shared storage. I've setup iSCSI with Xen and maintained it using CentOS (RedHat Enterprise Linux, or RHEL), even in a clustered configuration. When architecting this sort of solution -- you really have to look at all the dependencies you create, otherwise you're just adding more headache. For an introduction to the subject, check out this article on Live Migration of Xen Domains.

While separating out every service into its own guest seems like a great idea at first, it also would require installing many OSes and keeping them all up-to-date with patches. This would seem to lessen the security since most people install an OS using a CDROM or DVD using default configurations. They don't want to take the time to setup and manage "more" machines, when they already have their fill with the current situation/mess they are in.

Enter VMcasting. VMcasting allows package updates to be distributed via RSS feeds to the guests. I had first heard about VMcasting from a company who makes both Enterprise Xen control software, as well as an open-source version -- Enomalism. Enomalism has features that are very different than most of the other Xen Enterprise managers, including VMcasting. It supports sHype (a hypervisor access-control system similar to SELinux or RACF, with support of RBAC and TE), a firewall management application, centralized user management with LDAP controls, and a custom web API written in -- you guessed it -- Ajax. I can't believe I just used Ajax and RSS in the same paragraph as describing the benefits of hardware virtualization as it applies to vulnerability management, but there you have it.

The additional benefit of Enomalism comes in the form of its EVA containers (Enomalism Virtual Appliances). An EVA is a package, but that package can contain multiple virtual machines, such as two web servers and two database servers. These can be pre-configured and ready to be put into a lab or staging environment right away. Speaking of labs, imagine setting up a security penetration-testing lab using EVA containers.

After recently also reading "Penetration Tester's Open-Source Toolkit, Volume 2", the updated section on Building Penetration Test Labsgives some excellent suggestions on using Pen-Test "system lab" LiveCD's for learning purposes. Booting from CDROM as a virtual environment takes a lot of the work out, but imagine if you combined it into a bootable Pen-Test "network lab" with an EVA package.

Check out the authors' website at DE-ICE.Net for a list of the LiveCD "system lab" packages. See if you can spend some time making them into an EVA container, but don't VMcast and accidentally upgrade all of the out-of-date packages! Also of note would be the SecurityDistro website, which lists many of the FOSS LiveCD projects -- be sure to check out their new Beta website portal (register and join the fourms!), which should roll into their main site very shortly.

Posted by dre on Tuesday, February 5, 2008 in Hacking, Linux, Security and Tech.

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