This indicates an attack attempt to exploit a Heap Buffer Overflow vulnerability in Apple QuickTime.
The vulnerability is due to an improper boundary check condition in the application when handling a QuickTime reference movie file when a malformed 'rnet' atom. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted QuickTime reference movie file.
Apple Computer QuickTime 7.7.3 and earlier versions
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the vendor provided patch available from the website.: