Cross-zone scripting vulnerability in Apple Quicktime 3 to 7.1.3 allows remote user-assisted attackers to execute arbitrary code and list filesystem contents via a QuickTime movie (.MOV) with an HREF Track (HREFTrack) that contains an automatic action tag with a local URI, which is executed in a local zone during preview, as exploited by a MySpace worm.
http://www.kb.cert.org/vuls/id/304064
http://www.gnucitizen.org/blog/backdooring-quicktime-movies/
http://lists.apple.com/archives/Security-announce/2007/Mar/msg00000.html