The 'cloud'. It's all around us. Many organisations are utilising cloud based services as part of their overall IT strategy. This could be in the form of large scale infrastructure such as servers and storage from the likes of Amazon, right through to smaller components such as particular business processes like identity management. Many Managed Service Security Providers (MSSP) provide a totally outsourced security model with many software components available on-line and on-demand via subscription pricing and the like.
Cloud security is a big concern and quite rightly so. There should be great emphasis on the necessary agreements that both the client and provider sign up to. SLA's for example should be well understand as well as provision demarcation points for things like server and hosting platforms. This helps to avoid the 'no it's on the OS it's your problem', 'well no, you told me to patch it...' issues.
Many issues have been raised regarding data storage with external providers. Data in-situ and data-in-transit is always a well discussed area. Encryption via transit over HTTPS/SSL/TLS is all quite well known with plenty of discussion around the coffee machine over what is the best way to encrypt data at rest - hardware based crypto processors, backup shredding and the like all good for a feisty talking point.
Whilst on the topic of data, multi-tenant providers are always under the microscope to avoid data bleeding - where one client can have access to another clients data. Strict separation of duties at both the logical access control level, right through to operational and physical separation need to be understood and managed.
Whilst all of this is important, it brings me to some simple points that I think are often overlooked. Security is best managed using a defence-in-depth or circles approach, with the protection of key information assets being complete when several thin layers of security are merged together. It's pointless having the best encrypted SAN in the western world if you don't have physical access control to the data centre. Having a complex password policy loses it's muscle if you don't have well managed access control lists on the data shares and so on. The same can be applied to cloud providers.
For example: to set up an account on any number of platform/server/data/hosting providers, you simply need an email address, password and valid credit card details. In a few minutes I could launch a few servers, copy several gigs of data, host a new web platform all with a few clicks. The one single entry point into that environment, which has just become an extension of my organisation's IT department, is an email address and password. Any attacker now has a much smaller attack space to hit. One password is what separates a malicious user to a host of services and data that are provided externally.
So, whilst the underlying components could be secured, the entry point to the externally provided components is actually much smaller.
It's often worth thinking like a user (sometimes a malicious user) when managing and implementing any external internet or 'cloud' based extension of your IT provision as it's always the smallest things which are often the most costly.