VP Innovation at Axway, Co-founder at Vordel

Mark O'Neill

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Are Users to Blame For Cloud Insecurity?

So who is to blame if a customer deploys an insecure application to the Cloud?

In an insightful post, Paul Miller asserts that "Cloud providers’ own systems will tend to be more secure than those that the majority of potential customers have in-house today". You may ask - So why is cloud security seen as a problem then? The problem, as he points out, is the customers who place insecure applications into those pristine, secure Cloud hosting environments:


The customers who open up all the ports you so carefully closed by default. The customers who use ‘password’ as their password. The customers who deploy sloppy code that’s riddled with holes. The customers who, frankly, are just human… and who don’t live and breathe security in the same way that at least someone inside the data centre probably does.
http://cloudofdata.com/2009/08/security-and-the-cloud-will-focus-shift-to-the-customer/

So who is to blame if a customer deploys an insecure application to the Cloud? Can you just blame the customer? It is not as easy as that...

Twelve years ago, I was working for an ISP and one of my jobs was to vet Perl and ASP scripts for security holes. If the ISP let a customer host an insecure script, who was to blame? Or does it even matter who to blame, after the damage is done? If the script could tie up resources on the system and degrade the performance of other customers' applications, then the ISP could not turn around and say "don't blame us, blame that other customer over there with their insecure script". In reality, we would block insecure applications before they were hosted.

The same went for SQL Server applications. Everyone seemed to use "sa" and a blank password. Does this mean SQL Server was inherently insecure? Arguably, yes (well, it was certainly not "secure by default" in those days). But in reality, it was up to the hosting provider to mitigate against the insecurity of applications and the insecurity of code. We could not just say "blame Microsoft".

Multi-tenancy
Although Paul Miller's blog post does not use the word "multi-tenancy", it is one of the keys here. Back in my ISP hosting days, we liked to think that we'd perfected "multi-tenancy", whereby the scripts of one customer could not interfere with the scripts of other customers. However, we still vetted the scripts for security holes.

The Cloud providers seem to take different tacks on this question.

I've noticed that Amazon will examine traffic to and from EC2 instances, and if they see evidence that a machine has been taken over by a bot or trojan, they then block traffic to it. This is like a "quarantine" approach - allow the customer to create an insecure EC2 image, but then detect its behavior and stop it from interfering with other EC2 images.

SalesForce take a different tack. They force developers to proactively add testing code to their applications written in the Apex language on the Force.com platform. Here is the section on Multi-Tenancy in the Force.com "Introduction to Apex":

Multi-tenancy

The Force.com platform is a multi-tenant platform, which means that the resources used by your application (such as the database) are shared with many other applications. This multi-tenancy has a lot of benefits, and it comes with a small promise on your part. In particular, if you write Apex code, the platform needs to do its best to ensure that it is well behaved.

For example, Apex code that simply loops will not benefit you (or the cloud). This is the reason why Apex, when deployed to a production server, needs 75% code coverage in tests.

The Apex runtime engine also enforces a number of limits to ensure that runaway Apex does not monopolize shared resources. These limits, or governors, track and enforce various metrics. An example of these limits include (at the time of writing): the total stack depth for an Apex invocation in a trigger is 16, the total number of characters in a single String may not exceed 100000, and the total number of records processed as a result of DML statements in a block may not exceed 10000.

There are various precautions that can be taken to ensure that the limits are not exceeded. For example, the batched for loop described earlier lifts certain limits, and different limits apply depending on what originated the execution of the Apex. For example, Apex originating from a trigger is typically more limited than Apex that started running as part of a web services call.

http://wiki.developerforce.com/index.php/An_Introduction_to_Apex

So SalesForce are effectively saying "We have a secure environment, and if you want to upload code to run on it, you have to make sure your code has built-in checks to ensure it does not inadvertently monopolize resources". Amazon seem to be taking the alternative approach of discovering if an app is misbehaving, and then quarantining it (of course, as IaaS, EC2 is quite different from Force.com which is PaaS, so their approach is different). It remains to be seen what approach is best. Customers can hedge their bets by using a Cloud Gateway to secure their data in the cloud, keeping it encrypted and signed, so that it is safe even if other apps in the multi-tenant environment misbehave.

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More Stories By Mark O'Neill

Mark O'Neill is VP Innovation at Axway - API and Identity. Previously he was CTO and co-founder at Vordel, which was acquired by Axway. A regular speaker at industry conferences and a contributor to SOA World Magazine and Cloud Computing Journal, Mark holds a degree in mathematics and psychology from Trinity College Dublin and graduate qualifications in neural network programming from Oxford University.