This indicates detection of multiple SQL logon attempts during a short period of time.
The repeated login attempts, at a rate of about 300 times in 10 seconds, may indicate that an attacker is attempting a brute force attack. Server responses to failed logins may facilitate this attack.
Oracle Application Server 9.2, 10.1 & 10.2
Impact of a successful attack could vary, with the worse case being a system compromise.
Adjust the threshold to your network.
Monitor the traffic from that network for any suspicious activity.