Buffer Overflow in Oracle 9iAS (#NISR20122001)

["David Litchfield" <david () nextgenss com>]

NGSSoftware Insight Security Research Advisory

Name:    Oracle PL/SQL Apache Module
Systems Affected:  Oracle 9iAS
Platforms:  Sun SPARC Solaris 2.6
   MS Windows NT/2000 Server
   HP-UX 11.0/32-bit
Severity:  High Risk
Vendor URL:   http://www.oracle.com/
Author:   David Litchfield (david () nextgenss com)
Date:   20th December 2001
Advisory number: #NISR20122001


Description
***********
The web service with Oracle 9iAS is powered by Apache and provides many
application environmentswith which to offer services from the site. These
include SOAP, PL/SQL, XSQL and JSP. Two security issues exists in the PL/SQL
Apache module - one a buffer overrun vulnerability and the second a
directory traversal issue. The directory traversal issue affects only
Windows NT/2000.


Details
*******
The PL/SQL module exists to allow remote users to call procedures exported
by a PL/SQL package stored in the database server. As part of the
functionality offered by the PL/SQL module it is possible to remotely
administer the Database Access Descriptors and from here access help pages.

Normally, access to the /admin_/ pages is restricted - a UserID and password
are required but not for the help pages however. A buffer overrun
vulnerability exists in the module whereby a request for an overly long help
page will cause the overflow overwriting the saved return address on the
stack. By overwriting this saved return address with an address that
contains a "call esp" or "jmp esp" instruction a potential attack would land
into the user-supplied buffer and any computer code in the buffer would be
executed.

On Windows 2000/NT the apache process is running is the security context of
the SYSTEM account by default so any code executed would do so without
inhibition and an attacker could gain complete control over this system
remotely.

The second issue relates to a double URL decoding problem that allows
attackers to make a special request for a "help" file and break outside of
the web root.


Fix Information
***************
NGSSoftware alerted Oracle to these problems on the 18th of November who
responded quickly with a patch. This patch has been available from the
Metalink site (http://metalink.oracle.com) for over a week and both Oracle
and NGSSoftware urge Oracle 9iAS customers to download and install this
patch if they have not already done so. Oracle's advisory on this issue can
be found at http://otn.oracle.com/deploy/security/pdf/modplsql.pdf.

Further to applying the patch it is suggested that the default "/admin_"
path be changed to something else. To do this edit the wdbsvr.app file
located in the $ORACLE_HOME$\Apache\modplsql\cfg directory. Edit the
"adminPath" entry.

A check for these issues has been added to Typhon II, of which more
information is available from the NGSSoftware website,
http://www.ngssoftware.com.