Message-ID: <8C06219D9AC04F1594F5A48FB5A01117@regulus>
Date: Fri, 18 Jul 2008 15:03:16 +0100
From: "David Litchfield" <davidl@...software.com>
To: <dbsec@...elists.org>, <bugtraq@...urityfocus.com>,
	<full-disclosure@...ts.grok.org.uk>, <websecurity@...appsec.org>
Subject: Lateral SQL Injection Revisited - No Special
	Privs Required

At the end of April 2008 I published a paper about a new class of flaw in
Oracle entitled "Lateral SQL Injection". 

The paper can be found here:
http://www.databasesecurity.com/dbsec/lateral-sql-injection.pdf

Essentially the paper details a way in which the attacker can manipulate the
environment to trick an Oracle database into using arbitrary SQL in DATE
functions and data. 

A number of people at the time dismissed it as irrelevant because the
attacker required the ALTER SESSIOn privilege. Well, as it turns out, you
don't need the ALTER SESSION privilege at all. Here's why: there are certain
ALTER SESSION statements that can be executed even though the user doesn't
have the ALTER SESSION privilege. The statements that can be executed
without the privilege include those that relate to National Language
Support. Thus a user without ALTER SESSION privileges can change the date
format and so employ a lateral SQL injection attack. The script below shows
this in action. We connect to a fully patched 11g server and confirm we only
have CREATE SESSION privileges - i.e. the minimum we need to connect to the
server - everyone gets this privilege. We then issue an ALTER SESSION
statement to try set SQL_TRACE to true. As expected this fails with an
insufficient privileges error. But then we issues an ALTER SESSION to set
the NLS_DATE_FORMAT and this succeeds. Lastly we call the SYSDATE function
to confirm it took.


C:\>sqlplus /nolog

SQL*Plus: Release 11.1.0.6.0 - Production on Fri Jul 18 14:47:17 2008

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

SQL> connect testuser1/testuser1
Connected.
SQL> select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION

SQL> alter session set sql_trace = true;
alter session set sql_trace = true
*
ERROR at line 1:
ORA-01031: insufficient privileges


SQL> alter session set nls_date_format='"'' and myfunc()=1--"';

Session altered.

SQL> select sysdate from dual;

SYSDATE
------------------
' and myfunc()=1--

SQL>

Thus we can see that no special privileges are required to effect a lateral
SQL injection attack. I suppose I should have spotted this at the time.
Cheers,
David

--
E-MAIL DISCLAIMER

The information contained in this email and any subsequent
correspondence is private, is solely for the intended recipient(s) and
may contain confidential or privileged information. For those other than
the intended recipient(s), any disclosure, copying, distribution, or any
other action taken, or omitted to be taken, in reliance on such
information is prohibited and may be unlawful. If you are not the
intended recipient and have received this message in error, please
inform the sender and delete this mail and any attachments.

The views expressed in this email do not necessarily reflect NGS policy.
NGS accepts no liability or responsibility for any onward transmission
or use of emails and attachments having left the NGS domain.

NGS and NGSSoftware are trading names of Next Generation Security
Software Ltd. Registered office address: 52 Throwley Way, Sutton, SM1
4BF with Company Number 04225835 and VAT Number 783096402

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

Powered by blists - more mailing lists