AUSCERT External Security Bulletin Redistribution

                   ESB-2001.244 -- ISS Security Advisory
                     Oracle Redirect Denial of Service
                               20 June 2001


        AusCERT Security Bulletin Summary

Product:                Oracle
Vendor:                 Oracle
Operating System:       Windows NT
Impact:                 Denial of Service
Access Required:        Remote

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Internet Security Systems Security Advisory
June 19, 2001

Oracle Redirect Denial of Service

Internet Security Systems (ISS) X-Force has identified a vulnerability
with redirected Oracle connections. This vulnerability allows an 
unauthenticated user to consume all the memory on an Oracle server. It
is also possible for remote users to deny access to all other users and
cause the operating system to crash.

Affected Versions:
This issue is found on all versions of Oracle on Windows NT.

This vulnerability causes a Windows NT system to consume 100% of 
available memory. Access to the server is denied and a full reboot is

For Oracle on Windows NT, the Oracle listener process redirects
connection requests to a new port and the Oracle Database server creates
a new thread for this port. If a connection to the port is not made, the
thread and consumed memory is lost until the Oracle Database server is
restarted. By repeatedly requesting to be redirected and not connecting
to the waiting port, an Oracle server can be forced into consuming all
memory on the server. Once all memory has been consumed on the server,
any attempt to log in to the console results in crashing the operating

There is an immediate workaround for this security vulnerability. 
Oracle Net8 (formerly Oracle SQL*Net) has a feature called “valid node 
checking” that can be used to allow or deny access to Oracle server 
processes from network clients with specified IP addresses.

The following parameters can be established in PROTOCOL.ORA, a 
configuration file of Oracle Net8 to implement the valid node checking

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

The first parameter turns on the valid node checking feature. The latter
two parameters respectively specify the IP addresses that are permitted
to make network connections or denied from making network connections to
the Oracle server processes.

A combination of the parameters listed above can effectively prevent the
Oracle database server from consuming Windows NT memory in the manner 

ISS Database Scanner scans Oracle, Microsoft SQL Server, and Sybase
Adaptive Server for potential security vulnerabilities and provides the
ability to assess and reduce misconfigurations in Oracle installations.
ISS Consulting also provides a variety of database security offerings,
including development of security policy, security assessments, and 
penetration testing.

This vulnerability was researched by Jon Isaac of Internet Security
Systems. ISS would like to thank Oracle for their response and handling
of this vulnerability.

Additional Information:
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2001-0513 to this issue. This is a candidate for inclusion in
the CVE list <http://cve.mitre.org>, which standardizes names for 
security problems.


About Internet Security Systems (ISS) 

Internet Security Systems is the leading global provider of security 
management solutions for the Internet, protecting digital assets and 
ensuring safe and uninterrupted e-business. With its industry-leading 
intrusion detection and vulnerability assessment, remote managed 
security services, and strategic consulting and education offerings, ISS
is a trusted security provider to more than 8,000 customers worldwide
including 21 of the 25 largest U.S. commercial banks and the top 10 U.S. 
telecommunications companies. Founded in 1994, ISS is headquartered in 
Atlanta, GA, with additional offices throughout North America and 
international operations in Asia, Australia, Europe, Latin America and
the Middle East. For more information, visit the Internet Security 
Systems web site at www.iss.net or call 888-901-7477.

Copyright (c) 2001 Internet Security Systems, Inc.

Permission is hereby granted for the redistribution of this Alert
electronically. It is not to be edited in any way without express
consent of the X-Force. If you wish to reprint the whole or any part of
this Alert in any other medium excluding electronic medium, please
e-mail xforce@iss.net for permission.


The information within this paper may change without notice. Use of this
information constitutes acceptance for use in an AS IS condition. There
are NO warranties with regard to this information. In no event shall the
author be liable for any damages whatsoever arising out of or in 
connection with the use or spread of this information. Any use of this
information is at the user's own risk.

X-Force PGP Key available at: http://xforce.iss.net/sensitive.php
as well as on MIT's PGP key server and PGP.com's key server.

Please send suggestions, updates, and comments to: X-Force
xforce@iss.net of Internet Security Systems, Inc.

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