When thinking about protecting data in the cloud, there are three areas of use that security and privacy professionals need to consider: data in motion, data at rest and data in use. In a nutshell, the data leaves your environment and goes from to point A (your network) to B (the cloud); within point B it gets initially processed and stored within a database, and then is pulled out of that database for processing. Each of these phases carries risk:
- The first area, data in motion, is the most well known and understood. The goal of protecting data in motion is to prevent a third party from eavesdropping on a conversation on the transmission wire.
- The next key area, data at rest, is also relatively well understood. Data at rest is essentially the data that is stored persistently in some form, as a file, in a database, etc. The goal of protecting data at rest is to prevent a third party from reading the data, should they gain access to the data in its persistent form (for example, when an attacker gains access to the file system and opens or copies the files).
- Data in use is, effectively, the data that has been loaded into a process and is in the memory of the program that is running. In general, this data is in the clear while being processed and is typically not protected by techniques such as the in-cloud based encryption provided by Cloud Service Providers (CSPs).
In each of these three phases, there are security mitigation techniques that address the corresponding issues. Several approaches need to be evaluated, and at minimum, enterprises need to explore what their CSPs have to offer:
Data in Motion: Cryptographic protocols, such as Secure Sockets Layer (SSL) or Transport Layer Security (TLS), are typically used for protecting data in motion by establishing an encrypted and authenticated channel. Note that the data payload inside the transportation layer is still in the clear, so exploring encrypting the data itself versus (or in addition to) encrypting the wrapper should be evaluated.
Data at Rest: To protect this data, database solutions used by CSPs offer a variety of tools for encryption operations, such as transparent data encryption (which encrypts the database blocks on disk) or column encryption (which directly encrypts the column values). Moreover, there are several techniques that can be employed to encrypt file contents including encrypted file systems and block level encryption techniques.
You should note that a big concern regarding the encryption of data at rest in a cloud environment is who owns the keys, and where the keys physically reside. The benefits of data at rest protection are somewhat weakened if the data, and the key used to encrypt the data, are both stored in a less trusted security zone, such as the CSP’s environment. In response, CSPs are innovating in this space and are developing techniques whereby the enterprise, not the cloud service provider, can at least virtually owns the keys securing data at rest (even though they physically reside elsewhere).
Data in Use: In this case, data is in the clear while being processed and is not protected by techniques such as the in-cloud based encryption provided by the CSP. The Cloud application actually needs to decrypt data from its encrypted at rest state in order to perform any and all required application processing within the CSP datacenter. A new category of technologies focusing on data protection -- dubbed by Gartner as cloud access security brokers (CASB) -- is a solution to explore here. These solutions can encrypt data before it leaves the enterprise to provide protection during the data in use phase, as well as the other data lifecycle phases. Enterprises considering these technologies should ensure that they evaluate them to identify any impact they may have on the functionality of their cloud applications. (Disclosure: Perspecsys is one of many CASB vendors with this technology).
As cloud adoption pushes greater volumes of sensitive and regulated data into cloud-based SaaS applications, it’s more important than ever for security and compliance professionals to ask the right questions about where cloud data is flowing, who has access to it and what protection mechanisms can be put in place to mitigate risks.