This indicates an attack attempt against a denial-of-service vulnerability in Oracle Database Server.
The vulnerability is caused by an error when the TNS Listener component handles a specially crafted TNS data packet.
Oracle Oracle9i 188.8.131.52
Oracle Oracle9i 184.108.40.206dv
Oracle Oracle10g 10.1.0.5
Oracle Oracle10g 10.2.0.4
Oracle Oracle11g 220.127.116.11
Denial of service
Apply the patch released by the vendor: