David Chandler's Journal of Java Web and Mobile Development

  • David M. Chandler

    Web app developer since 1994 and Google Cloud Platform Instructor now residing in Colorado. Besides tech, I enjoy landscape photography and share my work at ColoradoPhoto.gallery.

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    June 2011
    S M T W T F S
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Are Private Clouds Really Safer?

Posted by David Chandler on June 24, 2011

For the second time in two weeks (first in Detroit, then in Atlanta), I’ve listened to a panel discussion on cloud computing in which a panelist has claimed that private clouds are safer than “The Cloud.” In both cases, the panelist was a data center vendor (hmmm…) and in both cases, the other panelists were not so readily agreed. The vendor rep in Atlanta kept mentioning the possibility of network sniffing, as though someone might be able to penetrate Amazon’s hardware virtualization, gain access to the real Ethernet controller, put it in promiscuous mode, and then sniff traffic on … the one wire running to the switch?

Bob Reid of the kotter group asked the best question of the evening: is there any empirical evidence that public cloud computing is safer than private cloud? In other words, has anyone ever successfully penetrated Amazon’s hardware virtualization, App Engine’s VM, etc. and used it to obtain other customers’ data? Said data center vendor acknowledged that social engineering is a much more likely attack vector and can be used just as successfully in a private cloud as public, but then repeated his concerns about the public cloud without citing any evidence. Thankfully, Dennis Hurst, founder of the Cloud Security Alliance, nailed it: the studies show that most break-ins are due to application design flaws and have nothing to do with the hosting environment.

There’s no doubt that some CxOs get a warm fuzzy from knowing that their data is on “their own” servers; however, this would appear to be a false sense of security. If anything, public cloud providers are safer (Dennis Hurst alluded to this earlier in the discussion) because security is an inherent design consideration. All public cloud providers rely on some form of virtualization, whether at the hardware layer (AWS) or a Java VM with security restrictions like App Engine and no doubt do continuous testing to ensure the security of the virtualization layer. The strength of the security sandbox is fundamental to the offering, and public cloud providers can afford to employ the best and brightest to get it right (unlike regional data center vendors–are you sure you’ve got the latest patches?).

Furthermore, public cloud offerings are typically built around services like AWS’s SimpleDB and App Engine’s Datastore, which are not subject to attacks like SQL injection because the service APIs don’t allow you to execute arbitrary database commands. Service APIs significantly limit attack surface, which is one reason why I prefer App Engine’s approach to virtualization over Amazon’s (granted, I’m a little biased). With AWS, you’re still responsible to configure your virtual machine instances correctly, albeit you have to explicitly open network ports so you’re not wide open by default.

The question, I think stands: is anyone aware of an incident in which a public cloud customer obtained access to another customer’s data by penetrating the security sandbox? Methinks the cloud offerings of today are generally much safer than the shared Web hosting arrangements of the past because of the superior virtualization technology employed today. Once upon a time, you could use CFFILE on a mis-configured ColdFusion host or similar technique in ASP to gain access to the file system on the shared host. But as far as I know, no one has demonstrated such an exploit against AWS, App Engine, Azure, etc.

Social engineering, insider leaks, and application flaws (which are arguably *less* likely using public cloud services) remain the most likely attack vectors, and CxOs should carefully evaluate FUD from data center vendors before rejecting the public cloud on the basis of security concerns. And while I’m at it, unless a “private cloud” offers elasticity, multi-tenancy, and metered service, I don’t think it can properly be called cloud. Dedicated / colocated hosting has been around for a long time and has its merits, but please don’t “cloud” the vocabulary.

One Response to “Are Private Clouds Really Safer?”

  1. breid8074 said


    Excellent post. I just wanted to deal with the folklore that private is naturally safer – at least that is what I encounter in the market. Is there empirical data to support the private vs public argument. Seems that this would be an easy thing to test. Compile a list of all the known data losses in the last year, weight each one by a measure of the relative magnitude and divide between private and public network. I would venture that only 20% was in the public network, but I am willing to be corrected.

    Best, Bob

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