About covert timing channels in OS Android

Two new covert timing channels are discovered in Android software. The first one is found in the last versions of Android OS. It is based on changing the size of free space in the file system. Two malwares can use this channel for hidden communication. Two applications are developed for testing the channel. It is shown that its capacity equals 20 b/s. The second covert channel is based on a time difference for execution of a system function with some fixed secret and various open (controlled by any user) data. An information flow through the channel is realized from a legal application to a malware without permission of the legal application.