From: Erez (schwarz@esecurity.co.jp)
Date: Wed Aug 03 2005 - 02:54:23 EDT
Joe hi,
A few things about Oracle and the 'listener' service. It is a process that
accepts and manages connections from the client to the Oracle database. The
listener provides the capability to remotely manage the listener. It has
separate authentication and auditing, it runs as a separate process and it
accepts commands and performs tasks outside the database. In the past this
would have allowed a remote user to execute commands like: STOP, RELOAD,
and SET LOG_FILE on the listener. In response to your second question, there
are tools that will allow you to interact with the Listener service in this
way, for example you can find a utility called tnscmd.pl that is freely
available, that allows you to issue a STOP command and this would 'stop' the
Listener service - which means that no one could connect to the database.
This is of course was very undesirable (and of course very dangerous).
Oracle's response was to issue a patch that updated the listener.ora file
and added a ADMIN_RESTRICTIONS_listener_name=ON parameter. The
ADMIN_RESTRICTIONS flag disables the ability of the listener controller to
set parameters, thereby not allowing remote users to set parameters.
Unfortunately the default setting when the Listener service is installed is
OFF! Most of the databases that I have seen have had this setting turned
'OFF'!!!
You can find a slightly old explanation on Listener manipulation at:
http://www.jammed.com/~jwa/hacks/security/tnscmd/tnscmd-doc.html by jwa, he
also wrote & published the tnscmd tool.
The explanation by jwa is a bit dated now, but once you start experimenting
with later versions, you will no doubt discover many very interesting
reactions and occurrences.
Also check out the EXTPROC(external procedure) vulnerabilities. This is a
service that allows PL/SQL packages to load and call functions in operating
system DLLs and shared libraries . When a call to load a function in an
external library is made, the Oracle process contacts the Listener process.
The Listener process in turn connects to the EXTPROC service and passes the
name of the library and the requested function to it. You may ask how the
EXTPROC service authenticate the user, well it doesn't!! You can issue
requests to the Listener process to call functions in the external operating
system libraries. Oracle responded by changing this functionality in the
next version 9.2(something). Now all the failed calls would get logged to a
file. If you enter an overly long string it overwrites the saved return
address allowing you to execute your own code. Oracle came out with a patch
to solve this problem as well.
By the way there are much quicker & easier ways to 'own' an Oracle database
then attacking the Listener.
Erez Schwarz
-----Original Message-----
From: Joe T [mailto:recommendeddosage@gmail.com]
Sent: Wednesday, August 03, 2005 12:55 AM
To: pen-test@securityfocus.com
Subject: Oracle Auditing
Good day,
I should preface this message by saying that I have little to no
experience with Oracle administration, and I'm looking to gain a bit
of information.
When performing some network scans, I notice that the Oracle database
rarely has a password set for the tnslsnr account. From the Nessus
scan results, I have learned that the database may be compromised
because of this null password. I've searched the web, and the majority
of the information I find talks about a DoS attack for Oracle 8.
My question becomes: Has anyone exploited this misconfiguration, and
if so - how? Is this an account that you can connect to without
expensive Oracle software?
Also, what other tools do you utilize to audit Oracle?
Thank you,
Joe
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