  Due to the increasing security standards of modern smartphones, forensic data
acquisition from such devices is a growing challenge. One rather generic way to
access data on smartphones in practice is to use the local backup mechanism
offered by the mobile operating systems. We study the suitability of such
mechanisms for forensic data acquisition by performing a thorough evaluation of
iOS's and Android's local backup mechanisms on two mobile devices. Based on a
systematic and generic evaluation procedure comparing the contents of local
backup to the original storage, we show that in our exemplary practical
evaluations, in most cases (but not all) local backup actually yields a correct
copy of the original data from storage. Our study also highlights corner cases,
such as database files with pending changes, that need to be considered when
assessing the integrity and authenticity of evidence acquired through local
backup.
