CORE SDI
                                   http://www.core-sdi.com

           Vulnerability Report For Netscape Servers Heap Buffer

Overflow

Date Published: 2000-10-31

Advisory ID: CORE-2000103101

Bugtraq ID: 1865

CVE CAN: Non currently assigned.

Title: Netscape Servers Heap Buffer Overflow

Class: Boundary Condition Error (Buffer Overflow)

Remotely Exploitable: Yes

Locally Exploitable: Yes

Release Mode: USER RELEASE

Communications with the vendor have been remarkably difficult
and to a large degree unproductive. Our last point of contact
was October 18, 2000. This last communication stated that
they would getting back to us shortly.
Twelve days and several emails later we have decided to
release without vendor support as it seems unlikely to be
forthcoming.

Vulnerability Description:

An exploitable heap buffer overflow vulnerability was discovered in
the Netscape Directory Server product.
The Netscape Certificate Management System also has several server
components that share the problem.
Vulnerable systems allow the execution of arbitrary code as the user
running
the services.

Vulnerable Packages/Systems:

Netscape Certificate Management System 4.2 (Microsoft Windows NT 4.0
version)
Netscape Directory Server 4.12 (Microsoft NT 4.0 version)

Solution/Vendor Information/Workaround:

Contact the vendor for a fix. Patches for iPlanet
products are usually available from:

http://www.iplanet.com/downloads/patches/index.html

Additionally, advisories and information on security issues
of these particular Netscape products can be obtained from:

iPlanet Certificate Management System
http://www.securityfocus.com/bid/1839
http://www.securityfocus.com/bid/676

Netscape Directory Server
http://www.securityfocus.com/bid/1839
http://www.securityfocus.com/bid/676

Vendor notified on: October 2nd. 2000

Last contact with the vendor was on October 18th, 2000
when CORE SDI was informed that a patch for a problem
reported previously was available and that information
and a status report for the vulnerability described
in this advisory would be available later that day.
Since then no communication from the vendor was
received, even after two emails asking for
an update on October 23rd. and October 30th.

Credits:

This vulnerability was found by Emiliano Kargieman and
Agustin Kato Azubel from Core SDI S.A.

This advisory was drafted with the help of the SecurityFocus.com
Vulnerability Help Team. For more information or assistance
drafting advisories please mail [email protected].

Technical Description - Exploit/Concept Code:
The Netscape Directory Server 4.12 provides a Web to LDAP gateway,
by means of the Directory Services Gateway (DSGW) web server.
No authentication credentials are required from the client to access DSGW.
The same service is installed and used as part of the Certificate
Management
System (Netscape/iPlanet CMS 4.2) and in this case it listens on a tcp
port chosen during the installation process (24326/tcp in this example)

A request with an URI as follows:
http://server:24326/dsgw/bin/search?context=<1011 'a' chars>
will overflow a buffer located in the heap.

This buffer is allocated at 404501 with a call to an internal
function that ends up calling MSVCRT!malloc. The buffer is allocated
with a fixed size of 1024 bytes.
Then at 40455B a call to sprintf is made like this:
sprintf(pFixedBuffer, "%s$$LANGDIR/%s.conf", "…/context/", userbuff);
since sprintf doesn't do any bounds checking, the buffer can be
overflowed depending on the size of 'userbuff' which is the
argument the user specifies to the 'context=' parameter when
calling the vulnerable program. A string of 999 bytes is
enough to overflow the 'pFixedBuffer' by 1 byte and cause
an exception.

Due to the nature of the data overwritten, this vulnerability
could be exploited, being possible to execute arbitrary machine code.

The same problem seems to be present in almost all the binaries (12)
in the Netscape\Server4\dsgw\bin directory (except for tutor).

DISCLAIMER:
The contents of this advisory are copyright (c) 2000 CORE SDI S.A.
and may be distributed freely provided that no fee is charged for this
distribution and proper credit is given.

$Id: Netscape-Servers-advisory.txt,v 1.3 2000/10/31 22:47:47 iarce Exp $

"Understanding. A cerebral secretion that enables one having it to know
a house from a horse by the roof on the house,
It's nature and laws have been exhaustively expounded by Locke,
who rode a house, and Kant, who lived in a horse." - Ambrose Bierce

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