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 vulnhelp@securityfocus.com.



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 $

---



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Presidente

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email   : iarce@core-sdi.com

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Tel/Fax : +(54-11) 4331-5402

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