Cloud Security for Home and SMB

I see increasing evidence that the cloud is drifting into the home and small to midsize business (SMB) market. This is a great thing for security, but also should raise concern.

Take for example inexpensive network attached storage (NAS) devices. Only a few hundred dollars will get a self-contained box with RAID and network services. Several terabytes in a redundant array on the network is a great thing for a home or SMB that wants to safely back up data. The next step in data availability is to start to rotate backups to an off-site location.

Enter the cloud.

Service providers like DropBox or CTERA offer to replicate the data from a NAS. Here is some typical marketing information I found on the CTERA site:

Before data is sent from the Cloud Attached Storage appliance to its online backup destination, it is encrypted using 256-bit AES (Advanced Encryption Standard). This is a highly secure encryption algorithm, approved as safe enough for protecting U.S. government classified material, and widely used by banks.

Highly secure? Very convincing. Oh, wait, do they mean widely used by the government agencies and banks that still get breached? I do not find this kind of vague industry reference very reassuring, but maybe I know too much. They also offer SSL for confidentiality in transmission and SHA-1 for data integrity. Nice to see standards.

Moving on, I noted their explanation of key management. After all, this is what really matters in the world of encryption when it comes to getting a secure service.

Passwords are required to access online backup versions of your data. You may choose between two options of passphrase protection:
* An automatically-generated key: This offers the ability to reset the key if it is forgotten.
* A personal passphrase: In this case, you choose a passphrase known only to you. While this offers an additional level of privacy, it also means that if the passphrase is forgotten, the protected data will not be retrievable at all.

The first option is not explained clearly. Many consumers probably will not realize that the ease of resetting a key is inversely related to the safety of their data in the cloud. How is the reset handled? I see the “additional level of privacy” in option two as really the baseline, not something extra. I would warn customers that using a reset option is below a baseline of privacy, like leaving their front door key under the mat.

A big question for the cloud provider is whether there is more risk in someone attacking the reset mechanism and compromising encrypted storage or if there is more risk in customers losing their keys. Helpdesk and support costs might typically be considered higher for more secure options. However, it seems to me that since they offer a backup service and not primary data access they should still encourage customers to lean away from any convenient reset options. Alternatively they could add support for change/access logging and alerting for data in the cloud.

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