Tech Insight: Securing The Virtualized Server Environment

Server virtualization is becoming all the rage in many data centers as enterprises seek greater efficiency and cost savings by consolidating their hardware. Unfortunately, some of these enterprises have overlooked the security implications of virtualizing their environments -- but hackers and security researchers haven't.

At ShmooConearlier this month, security pros had a chance to get an up-close-and-personal look at one of the newest, previously unreleased exploits for the virtualized server environment. While not quite a zero-day vulnerability (the researchers worked directly with VMware before releasing details), the directory traversal exploit against VMware Server and ESX/ESXi is still catching virtual server admins with their pants on the ground.

Justin Morehouse and Tony Flick's presentation, "Stealing Guests...theVMware Way," detailed the attack and included an easy-to-use tool that would allow an unauthenticated attacker to download any guest virtual machine from an affected system. Even without the tool, the attack was simple enough to carry out with a Web browser -- throw in a quick search with Shodan, and well, you know what they say about "idle hands."

Still feeling insecure about choosing to virtualize your servers? You're not alone. According to the CDW's "Server Virtualization Life Cycle Report: Medium and Large Businesses," 17 percent of IT executives said their most significant barrier to server virtualization was concern about security. Concerns such as these may be one reason why only 37 percent of data and application have been virtualized.

But virtualization efforts are ramping up quickly, according to a Gartner study that predicts approximately 50 percent of x86 architecture server workloads will be virtualized by the end of 2012. The added complexity of virtualization could decrease visibility into network traffic and the data flowing in and out of sensitive servers; it could also create questions as to whether one virtual system compromise will affect other virtual guest systems. Ultimately, the question is: How do you know your data is secure in your virtual environment?

The answer? Get back to the basics. Just like physical servers and networks, virtual systems need security controls to protect and monitor sensitive data to make sure it's not being leaked, intentionally or unintentionally. But instead of physical appliances that can be seen and touched -- and fail -- we now need "virtual" security appliances. The low profile of virtual security appliances allows quick deployment, utilization of the existing virtual infrastructure, and quick failover and restoration from backup if something fails.

The primary benefit of specialized, virtual security appliances and products that integrate with the hypervisor is they allow security to regain the visibility and control of traffic that is lacking in most virtualized server environments. Network security vendors like Lancope, Reflex Systems, and Altor have all released products for the virtual environment, offering a range of capabilities from network behavioral analysis to firewalls. As with physical firewalls and network flow data analyzers, you're implementing the same kinds of rules as if the virtual servers you're protecting were physically separated on the network.

Using virtual security appliances means you don't have to allocate rack space, power, or cooling to another specialized appliance -- one more step toward "green" IT environments. As you can probably imagine, product evaluations of virtual security appliances are also much easier than with physical devices because there's no need to ship expensive and heavy equipment back and forth. Loading up a new virtual machine is a breeze compared to unpacking, racking, and cabling a new physical appliance.

Traditional security products that have not been, or cannot be "virtualized," still have a place in the shared environment. Antivirus, host-based intrusion prevention, agent-based solutions, and similar security tools can, and should, be installed on the guest virtual machine just as you would have them on a physical machine. There is the rare occasion where physical and virtual systems aren't compatible, but most traditional security tools will behave as normal when connected to a virtual server.

A quick word of warning, however: Some software vendors do not officially support their software on virtual machines. Think about that before proceeding because it could be a problem down the road if you ever need support. If this is the case -- and you're not married to your current vendor -- then it might be time to start looking for another. Eleven percent of respondents in CDW's virtualization report cited vendor support of business applications as one of the barriers to virtualization.

In keeping with the back-to-basics theme, every enterprise should be reminded of solid system hardening practices. In addition to hardening the guest operating system and applications, special attention needs to go into hardening the virtual platform that the guests are running on. Hardening guides -- such as the recent draft release for VMware's vSphere 4.0 -- have been created for the popular virtualization platforms, including VMware, Xen, and Hyper-V. If you search Shodan for ESX (or similar terms), then you'll see there are some people who haven't bothered hardening their servers -- and left them wide open and Internet-accessible.

Virtualization doesn't have to be a dirty word when it comes to security. In fact, it has the potential to be a security enabler because it highlights the need for server admins and security people to work together to solve some of the problems posed by virtualizing servers. It's also an opportunity to explore new security tools and solutions that could provide more control and visibility than was available in the physical infrastructure.

Don't forget to apply the same security principles to virtual systems as you would for physical systems. In the end, they're all servers -- and someone somewhere is going to want to break into them.

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