When I started virtualizing production environment in 2002/2003 many people didn’t trust the technology and (to be honest) they didn’t understand the technology either. So I had to make big efforts in explaining the advantages of a virtual environment and the best of all arguments was to show them how it worked. Well, I guess I don’t have to explain it here anymore.

Still, when it comes to security, there are some more concerns providing a virtual environment. Let’s take a view on the following picture:

As we can see virtualization is adding a new layer that is susceptible to a new way of attacks and exploitation (after all it’s more software code and we all know what it means…) and we need to be aware of it and take the needed precautions as we always should do. This discussion becomes more important when is comes to high risk environments like in a DMZ.

Requirements for Virtual Environments

I’m not going to into the details of the security design of a virtual environment as it really depends on the goals you need to achieve.

Also I’m not talking about the security requirements of the virtual systems OS, this is out of scope, we’ll only talk about the underlying virtual environment. Although a secured operating system is a prerequisite in our case, there are plenty of guidelines on how to achieve this.

What I like to point here are the recommended security requirements for a virtual infrastructure architecture as schematic represented in the following picture:

We need to take particular care on the new administration environment and on the virtual network layer. As already suggested in the picture one recommendation is clear:

use an isolated administration environment

Managing several machines form a central site with special administration paths, makes the administration environment a clear target for attacks – Why should I attack several different systems when I can get it all at once? Therefore this is probably the best point to start in securing your environment. Make sure you also:

• define a controlled access to the administration environment and
• use a strong authentication where possible

Now let’s take a look a the virtual environments new attack areas as shown in the following picture:

Attack areas 1 to 3 are not so common, but the attacks on the administration infrastructure are well known and use the already known paths. This leads to the next recommendation:

keep your virtual environment up to date (including the management infrastructure)

It is crucial to keep those environment patched and if not possible: Implement workarounds (e.g. strict configuration settings) to lower the risk to an acceptable level.

Requirements for DMZ Virtual Environments

Particular attention on security requirement is needed in the DMZ (or higher risk) environments where following recommendation are a must:

• Security Domains: Do not share same host & network resources for different security domains.
• Secure Consolidated Logging: Log collection, consolidation, correlation, alerting & reporting (SIEM).
• Malware Detection: Like Intrusion Detection/Prevention.
• Vulnerability Management: Vulnerability scanning & reporting on network and system layer.
• Network Monitoring: NMS, Business View, KPI monitoring.
• Virtual Infrastructure Hardening: Baseline for Hypervisor, VM & Administration Infrastructure.

Of course those requirements make sense in every ICT environment, not only in the virtual ones.

Recommended VMware Baseline for DMZ

Now to bring some practical knowledge I’ll publish a VMware baseline excerpt that would make sense in our virtualized DMZ environment.

Applying to those recommendation and remembering that security is a process and every control should be monitored and verified, you should have no bigger risk in providing a virtualized DMZ environment.

References

• VMware Hardeninig Guides

About the Author

Andrea Covello has been working in information security since the 1990s. His strengths are in engineering, specializing in Windows security, firewalling and advanced virtualization.