This indicates an attack attempt to exploit a Buffer Overflow vulnerability in RealNetworks RealPlayer.
The vulnerability is due to an insufficient validation error when the vulnerable software handles a RMP files. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted RMP files.
RealNetworks RealPlayer 188.8.131.52 and prior
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version as suggested by the Vendor.