IOKit in Apple iOS before 7 allows attackers to send user-interface events to the foreground app by leveraging control over a background app and using the (1) task-completion API or (2) VoIP API.
http://www.securitytracker.com/id/1029054
http://support.apple.com/kb/HT5934
http://secunia.com/advisories/54886
http://lists.apple.com/archives/security-announce/2013/Sep/msg00006.html