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AUSCERT External Security Bulletin Redistribution
ESB-2001.265 -- COVERT-2001-03
Oracle 8i SQLNet Header Vulnerability
29 June 2001
AusCERT Security Bulletin Summary
Product: Oracle 8i Standard Edition
Oracle 8i Enterprise Edition
Operating System: Windows
Impact: Denial of Service
Access Required: Remote
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Network Associates, Inc.
COVERT Labs Security Advisory
June 27, 2001
Oracle 8i SQLNet Header Vulnerability
A vulnerability in the Oracle implementation of the TNS (Transparent
Network Substrate) over Net8 (SQLNet) protocol allows a remote user
to mount a denial of service attack against any Oracle service that
relies upon the protocol, including the TNS Listener, Oracle Name
Service and Oracle Connections Manager.
This vulnerability has been designated as CVE candidate CAN-2001-498.
RISK FACTOR: MEDIUM
o Vulnerable Systems
Oracle 8i Standard and Enterprise Editions Version 8.1.5, 8.1.6,
8.1.7 and all previous versions for Windows, Linux, Solaris, AIX,
HP-UX and Tru64 Unix.
o Vulnerability Overview
Oracle 8i database platform relies on multiple services for its
distributed client server computing functionality. Services that
are dependant upon the TNS include the TNS Listener, Oracle Name
Service and the Oracle Connections Manager. These servers accept
client requests and establish TNS data connections between the
clients and the services. TNS connections allow clients and services
to communicate over a network via a common API, regardless of the
network transport protocol used on either end (TCP/IP, IPX, etc).
Foundation of the TNS is the session layer protocol Net8 (SQLNet).
The services reliant upon the TNS protocol are critical to an
Oracle database environment. The TNS Listener is responsible for
maintaining remote communications with Oracle database services,
the Oracle Names Service implements database names resolution and
Oracle Connections Manager is responsible for managing connections
to the database services. In a default installation, the TNS
Listener resides on TCP port 1521, Names Service on TCP port 1575
and Connections Manager on TCP ports 1630 (gateway services) and
1830 (administration services).
A vulnerability exists in the TNS libraries which process Net8
(SQLNet) packets. This vulnerability will enable an attacker to
mount a denial of service attack against any of the above services
by issuing a malformed SQLNet connection request.
A Net8 (SQLNet) connection is made by the client sending an SQLNet
packet of Type-1 (NSPTCN) to the service, requesting a connection.
SQLNet packets contain a general header and type specific header
extensions. A Type-1 packet contains two fields in the type specific
header extensions that specify the offset and the length of the
connection data within the packet. These two fields are inadequately
verified, thus by specifying an offset which points to data beyond
the length of the packet, a memory read error is triggered, leading
to service termination.
The vulnerability occurs in an early stage of the packet processing,
before any authentication or verification of the content takes place.
This allows for unlogable, unauthenticated remote denial of service
Oracle has produced a patch under bug number 1656431 which is
available for download from the Oracle Worldwide Support Services
web site, Metalink (http://metalink.oracle.com) for the platforms
identified in this advisory. The patch is in production for all
supported releases of the Oracle Database Server.
PGP Security's CyberCop Scanner risk-assessment tool has been
updated to detect this vulnerability.
These vulnerabilities were discovered and documented by Nishad Herath
of the COVERT Labs at PGP Security.
o Contact Information
For more information about the COVERT Labs at PGP Security, visit our
website at http://www.pgp.com/covert or send e-mail to email@example.com
o Legal Notice
The information contained within this advisory is Copyright (C) 2001
Networks Associates Technology Inc. It may be redistributed provided
that no fee is charged for distribution and that the advisory is not
modified in any way.
Network Associates and PGP are registered Trademarks of Network
Associates, Inc. and/or its affiliated companies in the United States
and/or other Countries. All other registered and unregistered
trademarks in this document are the sole property of their respective
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