__________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
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             __________________________________________________________

                             INFORMATION BULLETIN

                    Vulnerabilities in Transarc DCE and DFS

September 18, 1996 17:00 GMT                                       Number G-46
______________________________________________________________________________
PROBLEM:       On systems running the DCE Distributed File System (DFS), users
               placed in more than NGROUPS_MAX-1 (usually 15) groups in the
               DCE registry and in /etc/group will have an incorrect grouplist
               upon login.
PLATFORM:      Systems running Transarc DCE and DFS 1.1 for Solaris 2.4 and
               Solaris 2.5.
DAMAGE:        Users with accounts on the system may gain unauthorized access
               to resources.
SOLUTION:      Apply the patches and/or workarounds listed in the vendor
               bulletin below.
______________________________________________________________________________
VULNERABILITY  This vulnerability is being widely distributed.
ASSESSMENT:
______________________________________________________________________________

[Begin Transarc Bulletin]

-----------------------------------------------------------------------

Topic:  Solaris AFS/DFS Integrated login bug if user is in too many
groups
Source: Transarc Corp.
---------------------------------

Problem: Vulnerability in Transarc DCE Integrated login for sites
running DFS


I. Description

On systems running the DCE Distributed File System (DFS), users placed
in more than NGROUPS_MAX-1 (usually 15) groups in the DCE registry and
in /etc/group will have an incorrect grouplist upon login.

For systems running both AFS and DFS, this limit is reduced to
NGROUPS_MAX-3 (13).

The vulnerability is caused by a change in the setgroups(2) system
call under DFS, which can cause it to fail when passed a large set of
supplementary groups.  Thus, it can cause problems in
non-Transarc-supplied programs which use setgroups(2) if they do not
handle error conditions correctly.

Vulnerable products include Transarc DCE and DFS 1.1 for Solaris 2.4
and Solaris 2.5.  This vulnerability is not present on sites not
running DFS (even if they are running AFS).


II. Impact

Users with accounts on the system may gain unauthorized access to
resources.  Access to resources controlled by DCE/DFS is unaffected,
as the DCE PAC is correct.

Users without accounts on the system cannot take advantage of this
vulnerability.


III. Solution

The following patches are available from Transarc:
        DCE/DFS 1.1 for Solaris 2.4:    patch 22
        DCE/DFS 1.1 for Solaris 2.5:    patch 2


A workaround is possible as well: simply ensure that no user is listed
in more than NGROUPS_MAX-3 groups in /etc/group (including the user's
primary group, which may not appear in /etc/group).  With this
workaround, only the primary group and groups which appear in
/etc/group will appear in the grouplist upon login.

Contact Transarc customer support by telephone at 412-281-5852 or
via email (dfs-help@transarc.com) for additional information or
questions.

IV.  Other Platform Impact

HP has advised that this problem does not affect the HP product.
IBM has advised that this problem does not affect the IBM product.

[End Transarc Bulletin]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of Transarc Corporation and CERT 
for the information contained in this bulletin.
_______________________________________________________________________________

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