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CERT Coordination Center

Oracle Database Server vulnerable to DoS via repeated requests to Oracle listener without connecting to redirected port

Vulnerability Note VU#105259

Original Release Date: 2001-12-08 | Last Revised: 2004-01-14


Oracle Database Server may consume all available memory and crash if clients do not connect completely in the expected manner.


When a connection request is made to Oracle for Windows NT, Oracle Database Server creates a new thread listening on a new port and redirects the connection to the new port. This new thread remains in memory listening until the client connects to its port or the Oracle Database Server is restarted.


By making many connection requests to Oracle without connecting to the new threads created to handle the connections, an attacker can force the server to consume all memory with listening threads. Once all server memory is consumed, the next console login attempt will crash the server.


The CERT/CC is currently unaware of a practical solution to this problem.

Enable tcp.validnode_checking and set tcp.invited_nodes and tcp.excluded_nodes to limit Oracle access to trusted hosts.

Set the following parameters in the Oracle Net8 configuration file PROTOCOL.ORA:

tcp.validnode_checking = YES
tcp.invited_nodes = {list of IP addresses}
tcp.excluded_nodes = {list of IP addresses}

Vendor Information


Oracle Corporation Affected

Notified:  August 27, 2001 Updated: November 17, 2001



Vendor Statement

"The information that you have posted ... is correct. Oracle has proposed the workaround to mitigate the vulnerability as described."

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

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Thanks to Internet Security Systems (ISS) for their advisory on this issue.

This document was written by Shawn Van Ittersum.

Other Information

CVE IDs: CVE-2001-0513
Severity Metric: 3.02
Date Public: 2001-06-19
Date First Published: 2001-12-08
Date Last Updated: 2004-01-14 20:43 UTC
Document Revision: 18

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