There is not a lot of doubt that cloud computing is the next frontier. Unfortunately, like for Far West, Cloud Computing will be in its early days a territory where the security may be weak (euphemism :Wink: ).

Already, a lot of effort is placed on analyzing the threats and finding solutions. In this trend, there is an interesting approach proposed by Thomas RISTENPART, Eran TROMER, Hovav SHACHAM and Stefan SAVAGE in their paper “Hey, You, Get off of My Cloud“. They discovered that a same server may run Virtual Machines (VM) for different customers. The goal of their attack was to plant a malicious VM on the same server than the target. Then, by measuring several parameters such as cache usage, or estimated traffic rates, they should be able to infer some information. In other words, a side channel attack.

Obviously the most questionable point is the first one. It has two assumptions:

• – Being able to co-reside on a server with the target. A complete section (number 7) proposes different strategies to succeed on Amazon’s EC2.
• – being able to implement a malicious VM for instance through existing vulnerability. This one seems even more questionable.

I am not sure that the disclosed attack is more than a nice theoretical play. Nevertheless, it has the advantage to rise many interesting questions. I’m sure that side channel attacks on cloud computing will become a very thrilling domain of exploration.

The paper was presented at CCS’09. Thomson was sponsor of one the hosted workshop (ACM DRM workshop 09)