  Steganographic methods allow the covert exchange of secret data between
parties aware of the procedure. The cloud computing environment is a new and
hot target for steganographers, and currently not many solutions have been
proposed. This paper proposes CloudSteg which is a steganographic method that
allows the creation of a covert channel based on hard disk contention between
the two cloud instances that reside on the same physical machine. Experimental
results conducted using open source cloud environment OpenStack, show that
CloudSteg is able to achieve a bandwidth of about 0.1 bps which is 1000 times
higher than is known from the state-of-the-art version.
