[SAMBA-SECURITY] CVE-2007-0453: Buffer overrun in nss_winbind.so.1 on Solaris

["Gerald (Jerry) Carter" <jerry () samba org>]

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==========================================================
==
== Subject:     Buffer overrun in NSS host lookup Winbind
==              library on Solaris
== CVE ID#:     CVE-2007-0453
==
== Versions:    Samba 3.0.21 - 3.0.23d (inclusive) running on
==              Sun Solaris
==
== Summary:     A potential overrun in the gethostbyname()
==              and getipnodebyname() in the nss_winbind.so.1
==              library on Solaris can potentially allow
==              for code execution.
==
==========================================================

===========
Description
===========

NOTE: This security advisory only affects Sun Solaris
systems running Samba's winbindd daemon and configured to
make use of the nss_winbind.so.1 library for gethostbyname()
and getipnodebyname() name resolution queries.  For example,

        ## /etc/nsswitch.conf
        ...
        ipnodes: files winbind
        hosts: files winbind

The buffer overrun is caused by copying a string passed
into the NSS interface into a static buffer prior to sending
the request to the winbindd daemon.


==================
Patch Availability
==================

A patch against Samba 3.0.23d has been attached to this
email.  This fix has be incorporated into the Samba 3.0.24
release.  Patches are also available from at the Samba Security
page (http://www.samba.org/samba/security).

==========
Workaround
==========

An unpatched Solaris server may be protected by removing
the 'winbind' entry from the hosts and ipnodes services in
/etc/nsswitch.conf.


=======
Credits
=======

This vulnerability was reported (including a proposed patch)
to Samba developers by Olivier Gay <ouah () ouah org>.   Much thanks
to Olivier for his cooperation and patience in the announcement
of this defect.  The time line is as follows:

* Dec 15, 2006: Defect first reported to the security () samba org
  email alias.
* Dec 21, 2006: Initial developer response by Andrew Tridgell
  confirming the issue.
* Jan 29, 2007: Announcement to vendor-sec mailing list
* Feb 5, 2007: Public issue of security advisory.


==========================================================
== Our Code, Our Bugs, Our Responsibility.
== The Samba Team
==========================================================

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diff -urN samba-3.0.23d/source/nsswitch/winbind_nss_solaris.c samba/source/nsswitch/winbind_nss_solaris.c
--- samba-3.0.23d/source/nsswitch/winbind_nss_solaris.c 2006-04-19 21:29:21.000000000 -0500
+++ samba/source/nsswitch/winbind_nss_solaris.c 2007-01-29 19:51:11.000000000 -0600
@@ -493,7 +493,8 @@
        af = AF_INET6;
 #endif
 
-       strncpy(request.data.winsreq, argp->key.name, strlen(argp->key.name)) ;
+       strncpy(request.data.winsreq, argp->key.name, sizeof(request.data.winsreq) - 1);
+       request.data.winsreq[sizeof(request.data.winsreq) - 1] = '\0';
 
        if( (ret = winbindd_request_response(WINBINDD_WINS_BYNAME, &request, &response))
                == NSS_STATUS_SUCCESS ) {
@@ -515,7 +516,8 @@
        ZERO_STRUCT(response);
        ZERO_STRUCT(request);
        
-       strncpy(request.data.winsreq, argp->key.name, strlen(argp->key.name));
+       strncpy(request.data.winsreq, argp->key.name, sizeof(request.data.winsreq) - 1);
+       request.data.winsreq[sizeof(request.data.winsreq) - 1] = '\0';
 
        if( (ret = winbindd_request_response(WINBINDD_WINS_BYNAME, &request, &response))
                == NSS_STATUS_SUCCESS ) {