[COVERT-2001-04] Vulnerability in Oracle 8i TNS Listener

[COVERT Labs <covert () nai com>]

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                       Network Associates, Inc. 
                   COVERT Labs Security Advisory 
                           June 27, 2001 

               Vulnerability in Oracle 8i TNS Listener


                           COVERT-2001-04 

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o Synopsis 

The Oracle 8i TNS (Transparent Network Substrate) Listener is 
responsible for establishing and maintaining remote communications 
with Oracle database services. The Listener is vulnerable to a buffer
overflow condition that allows remote execution of arbitrary code on 
the database server under a security context that grants full control
of the database services and, on some platforms, full control of the 
operating system.  Because the buffer overflow occurs prior to any 
authentication, the listener is vulnerable regardless of any enabled 
password protection. 

This vulnerability has been designated as CVE candidate CAN-2001-499.


RISK FACTOR: HIGH 
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o Vulnerable Systems 

Oracle 8i Standard and Enterprise Editions Version 8.1.5, 8.1.6,
8.1.7 and previous versions for Windows, Linux, Solaris, AIX, 
HP-UX and Tru64 Unix.

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o Vulnerability Overview

Client connection requests to a remote Oracle service are arbitrated
by the TNS Listener.  The TNS Listener accepts the client request and
establishes a TNS (Transparent Network Substrate) data connection
between the client and the service.  A TNS connection allows clients 
and servers to communicate over a network via a common API,
regardless of the network protocol used on either end (TCP/IP, IPX, 
etc). The TNS Listener must be running if queries are to be made by
remote clients or databases even if the network protocol is the same.
 
A default installation listens on TCP port 1521.

Listener administration and monitoring can be done by issuing
specific commands to the daemon. Typical requests, such as "STATUS", 
"PING" and "SERVICES" return a summary of listener configuration and
connections.  Other requests like "TRC_FILE", "SAVE_CONFIG" and 
"RELOAD" are used to change the configuration of the listener. An 
exploitable buffer overflow occurs when any of the command's 
arguments contains a very large amount of data.  

The TNS Listener daemon runs with "LocalSystem" privileges under 
Windows NT/2000, and with the privileges of the 'oracle' user under
Unix.  Exploitation of this vulnerability will lead to the remote
attacker obtaining these respective privileges.

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o Detailed Information:

The overflow can be triggered with a one-packet command conforming 
to the Net8 protocol. The client will send a Type-1 (NSPTCN) packet 
containing the proper Net8 headers and malformed command string with
embedded arbitrary code ("shellcode").  Although many of the TNS
listener's administrative commands can be limited to trusted users 
by enabling password  authentication, this vulnerability can 
nevertheless be exploited by  using unauthenticated commands such as
"STATUS".  It is important to  note that authentication is not
enabled by default.

The command string includes several arguments such as "SERVICE", 
"VERSION", "USER" and "ARGUMENTS". Any of these can be overfilled
with data to initiate the overflow.  Under both Windows and UNIX
platforms, an extended argument of several thousand bytes will 
induce a stack overflow.

Under Windows, the stack overflow will facilitate the execution of 
shellcode by manipulating the SEH (Strunctured Exception Handling) 
mechanism. Since the listener services runs as "LocalSystem", 
shellcode will be executed in the same security context. Under UNIX, 
the listener daemon will often be started by the "oracle" user
created during installation.  If this is the case, the attacker 
will gain the privileges of the database administrator.


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o Resolution 

Oracle has produced a patch under bug number 1489683 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.

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o Credits 

These vulnerabilities were discovered and documented by Nishad Herath
and Brock Tellier of the COVERT Labs at PGP Security.

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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 covert () nai com

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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
owners. 

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