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CERT* Vendor-Initiated Bulletin VB-97.12
October 24, 1997

Topic:  Potential denial of service attack in the OSF/DCE security server
Source: The Open Group


To aid in the wide distribution of essential security information, the CERT
Coordination Center is forwarding the following information from The Open
Group. Open Group urges you to act on this information as soon as
possible. Open Group contact information is included in the forwarded text
below; please contact them if you have any questions or need further
information.


=======================FORWARDED TEXT STARTS HERE============================

              Advisory on OSF/DCE Denial of Service Attack
                          October 23, 1997

   It has been discovered that OSF/DCE has a potential problem in the
   security server that could allow for a denial of service attack.

PROBLEM:
   If a principal, group, or organization is greater than 1024 characters
   (including the cell name, so the actual name limit is less than 1024)
   when passed to security daemon (secd), it will cause secd core dump.
   The buffer is overrun causing memory corruption.  In certain cases,
   the lookup attempt (or add or whatever) on the client will then
   rebind to another secd to make the request, eventually crashing
   all security daemons in the cell.

HOW TO AVOID:
   This potential denial of service attack has existed in all releases
   of OSF/DCE to date.  The Open Group sent a notification to all current
   DCE support licensees providing the following fix.  The Open Group is
   in the process of incorporating a fix for this defect to all future DCE
   maintenance releases.  The end-users may ask their DCE vendors for
   such a fix.

SOURCE CODE FIX:
   The quick fix is the following:
   In rsdb_name_util.c, the "rsdb_name_util_complete_name" routine
   should perform the following check after the ustrncpy.

   /* Retrieve the name_key record of the given domain directory.  */
   if(!check_domain(domain)) {
       SET_STATUS(st, sec_rgy_bad_domain);
       return false;
   }

   rsdb_util_get_key_of_id(domain, START_OF_LIST,
                            (Pointer)&name_key, &name_key_len);
   ustrncpy(complete_name, name_key.name, name_key.name_len);
   complete_name[name_key.name_len] = '\0';
   #ifdef FIX
      if (object_name_len < 1     ||
         object_name_len + name_key.name_len + 1 > sec_rgy_name_t_size - 1)
      {
          return false;
      }
   #endif /* FIX */

   if(object_name_len > 0) {
       ustrcat(complete_name, "/");
       ustrcat(complete_name, object_name);
   }
   return true;

CONTACT INFORMATION:

  The Open Group DCE Systems Engineering

  The Open Group
  11 Cambridge Center,
  Cambridge, MA 02142

  Telephone:  +1 617 621 8990
  E-mail:     dce-support-admin@opengroup.org


========================FORWARDED TEXT ENDS HERE=============================

Editor's NOTE:  

        CERT/CC has received information that the Silicon Graphics, Inc. 
        implementation of OSF/DCE is vulnerable to this denial of
        service attack.  For more information, please see Silicon Graphics
        Inc. Security Advisory, "OSF/DCE Denial of Service Attack", Number:
        19980601-01-PX, issued on June, 16 1998:

              http://www.sgi.com/Support/security/advisories.html

============================================================================

If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in the Forum of Incident Response
and Security Teams (FIRST). See http://www.first.org/team-info/.

We strongly urge you to encrypt any sensitive information you send by email.
The CERT Coordination Center can support a shared DES key and PGP. Contact
the CERT staff for more information.

Location of CERT PGP key
         ftp://ftp.cert.org/pub/CERT_PGP.key


CERT Contact Information
- ------------------------
Email    cert@cert.org

Phone    +1 412-268-7090 (24-hour hotline)
                CERT personnel answer 8:30-5:00 p.m. EST
                (GMT-5)/EDT(GMT-4), and are on call for
                emergencies during other hours.

Fax      +1 412-268-6989

Postal address
        CERT Coordination Center
        Software Engineering Institute
        Carnegie Mellon University
        Pittsburgh PA 15213-3890
        USA

CERT publications, information about FIRST representatives, and other
security-related information are available from
        http://www.cert.org/
        ftp://ftp.cert.org/pub/

CERT advisories and bulletins are also posted on the USENET newsgroup
        comp.security.announce

To be added to our mailing list for CERT advisories and bulletins, send your
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In the subject line, type
        SUBSCRIBE  your-email-address



* Registered U.S. Patent and Trademark Office.

The CERT Coordination Center is part of the Software Engineering
Institute (SEI). The SEI is sponsored by the U. S. Department of Defense.


This file: ftp://ftp.cert.org/pub/cert_bulletins/VB-97.12.opengroup



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