When using LinuxTaskController, localized files may become accessible to unintended users if permissions are misconfigured.

To enforce the accessibility of job files to only the job-owner and the TaskTracker, as per MAPREDUCE-842, it is trusted that the setuid/setgid linux TaskController binary is group owned by a special group to which only TaskTracker belongs and not just any group to which TT belongs. If the trust is broken, possibly due to misconfiguration by admins, the local files become accessible to unintended users, yet giving false sense of security to the admins.