NetBSD Security Advisory 2001-014: dump(8) exposes 'tty' group

[NetBSD Security Officer <security-officer () netbsd org>]

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                 NetBSD Security Advisory 2001-014
                 =================================

Topic:          dump(8) exposes 'tty' group 

Version:        NetBSD-current: source prior to August 8, 2001
                NetBSD 1.5.1:   affected
                NetBSD 1.5:     affected
                NetBSD 1.4.x:   all affected
                
Severity:       local users can gain tty group

Fixed:          NetBSD-current:         August 8, 2001
                NetBSD-1.5 branch:      August 8, 2001 (1.5.2 includes the fix)
                NetBSD-1.4 branch:      Pullups pending - apply the patch as
                                        explained below.


Abstract
========

The dump(8) command (installed as /sbin/dump) and the dump_lfs(8)
command (installed as /sbin/dump_lfs) are setgid tty.  dump(8) and
dump_lfs(8) did not drop those setgid tty rights while performing
functions other than those the rights were provided for, including
execution of a user supplied RCMD_CMD environment variable.


Technical Details
=================

dump(8) and dump_lfs(8) require tty rights in order to notify
members of the operator group to change backup media.  Since a user
can supply an executable as a method to access a remote dump device
by setting the RCMD_CMD environment variable, a local user can gain
tty privilieges for themselves.

With the supplied patch, dump(8) and dump_lfs(8) properly reserve
tty rights and activate them only for the intended use.


Solutions and Workarounds
=========================

The following instructions describe how to upgrade your dump(8)
and dump_lfs(8) binaries by updating your source tree and rebuilding
and installing a new version of dump(8) and dump_lfs(8).

* NetBSD-current:

        Systems running NetBSD-current dated from before 2001-08-08
        should be upgraded to NetBSD-current dated 2001-08-09 or later.

        The following directories need to be updated from the
        netbsd-current CVS branch (aka HEAD):
                basesrc/sbin/dump

        To update from CVS, re-build, and re-install dump and dump_lfs:
                # cd src
                # cvs update -d -P sbin/dump
                # cd sbin/dump

                # make cleandir dependall
                # make install
                # cd ../dump_lfs
                # make cleandir dependall
                # make install


* NetBSD 1.5, 1.5.1:

        Systems running NetBSD 1.5 or 1.5.1 sources dated from
        before 2001-08-08 should be upgraded from NetBSD 1.5.x
        sources dated 2001-08-09 or later.

        NetBSD 1.5.2 is not vulnerable.

        The following directories need to be updated from the
        netbsd-1-5 CVS branch:
                src/sbin/dump

        To update from CVS, re-build, and re-install dump and dump_lfs:

                # cd src
                # cvs update -d -P sbin/dump
                # cd sbin/dump

                # make cleandir dependall
                # make install
                # cd ../dump_lfs
                # make cleandir dependall
                # make install


        Alternatively, apply the following patch (with potential offset
        differences):
                ftp://ftp.netbsd.org/pub/NetBSD/security/patches/SA2001-014-dump-1.5.patch

        To patch, re-build and re-install dump and dump_lfs:

                # cd src/sbin/dump
                # patch < /path/to/SA2001-014-dump-1.5.patch

                # make cleandir dependall
                # make install
                # cd ../dump_lfs
                # make cleandir dependall
                # make install


* NetBSD 1.4, 1.4.1, 1.4.2, 1.4.3:

        The patch supplied for the 1.5 releases, also applies to
        1.4, 1.4.1, 1.4.2, and 1.4.3.

        Follow the instructions for using the patch as detailed in
        the NetBSD 1.5 section above.


Thanks To
=========

canis for raising the issue.

Matthew Green for a patch, and David Maxwell for revisions to the patch.

John Hawkinson for the patches for the NetBSD 1.5 branch.


Revision History
================

        2001-08-23      Initial release


More Information
================

An up-to-date PGP signed copy of this release will be maintained at
  ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2001-014.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/.


Copyright 2001, The NetBSD Foundation, Inc.  All Rights Reserved.

$NetBSD: NetBSD-SA2001-014.txt,v 1.8 2001/08/23 05:59:07 lukem Exp $

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