157 lines
6.3 KiB
Text
157 lines
6.3 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
|
|
Hash: SHA512
|
|
|
|
=============================================================================
|
|
FreeBSD-SA-16:36.telnetd Security Advisory
|
|
The FreeBSD Project
|
|
|
|
Topic: Possible login(1) argument injection in telnetd(8)
|
|
|
|
Category: core
|
|
Module: telnetd
|
|
Announced: 2016-12-06
|
|
Credits: Brooks Davis (sponsored by: DARPA, AFRL)
|
|
Affects: All supported versions of FreeBSD.
|
|
Corrected: 2016-12-06 18:52:02 UTC (stable/11, 11.0-STABLE)
|
|
2016-12-06 18:49:38 UTC (releng/11.0, 11.0-RELEASE-p4)
|
|
2016-12-06 18:52:18 UTC (stable/10, 10.3-STABLE)
|
|
2016-12-06 18:49:48 UTC (releng/10.3, 10.3-RELEASE-p13)
|
|
2016-12-06 18:49:54 UTC (releng/10.2, 10.2-RELEASE-p26)
|
|
2016-12-06 18:49:59 UTC (releng/10.1, 10.1-RELEASE-p43)
|
|
2016-12-06 18:52:33 UTC (stable/9, 9.3-STABLE)
|
|
2016-12-06 18:50:06 UTC (releng/9.3, 9.3-RELEASE-p51)
|
|
CVE Name: CVE-2016-1888
|
|
|
|
For general information regarding FreeBSD Security Advisories,
|
|
including descriptions of the fields above, security branches, and the
|
|
following sections, please visit <URL:https://security.FreeBSD.org/>.
|
|
|
|
I. Background
|
|
|
|
The FreeBSD telnet daemon, telnetd(8), implements the server side of the
|
|
TELNET virtual terminal protocol. It has been disabled by default in
|
|
FreeBSD since August 2001, and due to the lack of cryptographic security
|
|
in the TELNET protocol, it is strongly recommended that the SSH protocol
|
|
be used instead. The FreeBSD telnet daemon can be enabled via the
|
|
/etc/inetd.conf configuration file and the inetd(8) daemon.
|
|
|
|
After a user is connected, telnetd executes the login(1) program or a
|
|
similar program specified by the -p <loginprog> argument. In order to do
|
|
so, it constructs an array of command line arguments which are passed to
|
|
execv(3).
|
|
|
|
II. Problem Description
|
|
|
|
An unexpected sequence of memory allocation failures combined with
|
|
insufficient error checking could result in the construction and
|
|
execution of an argument sequence that was not intended.
|
|
|
|
III. Impact
|
|
|
|
An attacker who controls the sequence of memory allocation failures and
|
|
success may cause login(1) to run without authentication and may be able
|
|
to cause misbehavior of login(1) replacements.
|
|
|
|
No practical way of controlling these memory allocation failures is
|
|
known at this time.
|
|
|
|
IV. Workaround
|
|
|
|
No workaround is available, but systems not running the telnet daemon
|
|
are not vulnerable.
|
|
|
|
Note that the telnet daemon is usually run via inetd, and consequently
|
|
will not show up in a process listing unless a connection is currently
|
|
active; to determine if it is enabled, run
|
|
|
|
$ ps ax | grep telnetd | grep -v grep
|
|
$ grep telnetd /etc/inetd.conf | grep -vE '^#'
|
|
|
|
If any output is produced, your system may be vulnerable.
|
|
|
|
V. Solution
|
|
|
|
Perform one of the following:
|
|
|
|
1) Upgrade your vulnerable system to a supported FreeBSD stable or
|
|
release / security branch (releng) dated after the correction date.
|
|
|
|
2) To update your vulnerable system via a binary patch:
|
|
|
|
Systems running a RELEASE version of FreeBSD on the i386 or amd64
|
|
platforms can be updated via the freebsd-update(8) utility:
|
|
|
|
# freebsd-update fetch
|
|
# freebsd-update install
|
|
|
|
3) To update your vulnerable system via a source code patch:
|
|
|
|
The following patches have been verified to apply to the applicable
|
|
FreeBSD release branches.
|
|
|
|
a) Download the relevant patch from the location below, and verify the
|
|
detached PGP signature using your PGP utility.
|
|
|
|
# fetch https://security.FreeBSD.org/patches/SA-16:36/telnetd.patch
|
|
# fetch https://security.FreeBSD.org/patches/SA-16:36/telnetd.patch.asc
|
|
# gpg --verify telnetd.patch.asc
|
|
|
|
b) Apply the patch. Execute the following commands as root:
|
|
|
|
# cd /usr/src
|
|
# patch < /path/to/patch
|
|
|
|
c) Recompile the operating system using buildworld and installworld as
|
|
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
|
|
|
|
Kill any running telnetd processes, or reboot the system.
|
|
|
|
VI. Correction details
|
|
|
|
The following list contains the correction revision numbers for each
|
|
affected branch.
|
|
|
|
Branch/path Revision
|
|
- -------------------------------------------------------------------------
|
|
stable/9/ r309643
|
|
releng/9.3/ r309637
|
|
stable/10/ r309642
|
|
releng/10.1/ r309636
|
|
releng/10.2/ r309635
|
|
releng/10.3/ r309634
|
|
stable/11/ r309641
|
|
releng/11.0/ r309633
|
|
- -------------------------------------------------------------------------
|
|
|
|
To see which files were modified by a particular revision, run the
|
|
following command, replacing NNNNNN with the revision number, on a
|
|
machine with Subversion installed:
|
|
|
|
# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
|
|
|
|
Or visit the following URL, replacing NNNNNN with the revision number:
|
|
|
|
<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
|
|
|
|
VII. References
|
|
|
|
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1888>
|
|
|
|
The latest revision of this advisory is available at
|
|
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:36.telnetd.asc>
|
|
-----BEGIN PGP SIGNATURE-----
|
|
|
|
iQIcBAEBCgAGBQJYRw1uAAoJEO1n7NZdz2rnUC0P/3R7UoeNFknnYEXs25NnTS3h
|
|
oDZnGEbLloqQC4mAtPsC2v9WdSRh318J7UMOpko+uYlvxwsJe9TXRgUwP24atdtJ
|
|
a0Al8BvbmIHckIxG7cFJ6Xsw5NDXBgHo2JWBgdU2xvRafZYvFmjlGyxGrvg6Ok0s
|
|
LCz+cnOwni+J4R0CUHTb7eyoeW4HYsg5bVBnzmDwdqQTiig4PsIBVSu+VbOM8kTT
|
|
u7JCzxibzwm9TE0orxDBsY60//hbJRMm12SXj+tVJS3w+qK2iY+Aq02llyTqlGHd
|
|
Tpz4++d9UlS5QSPnu42ev/wzfPDZoxhbb5yciEUDSZA7vG5RD0pCfxfOf+8zORXA
|
|
PLp8XRrl76DJonULUjtNPo8xE3gFOztbUZyTFpxChXUPzZGp0oPRQgTIBTMEPejH
|
|
jC7O5ic0q7aA8UcQk5tqn6lNS6eK6z2UoKGYN4qCjTlC18s1u9dPwHzeSAzjg5YF
|
|
fHX0t/MB8zJ5ts0pUs6OTMOu6umrP4SUJF9hpACFG16vzjJ1S573tuPr9L4HMNCv
|
|
XTX9kjcFwmHqpbrFYW38Fk90x14TT3tigi+xYvCruS1XQeLQM48ThgYAdEboGJvT
|
|
8LGVI8rbwjaglrEk670RlnWVKQInqtPBmbV/GXL9AtE4zzsTHXDT/7iJ30pb4RJq
|
|
rA+cnK1Bog6FHCWGTxjF
|
|
=uYUg
|
|
-----END PGP SIGNATURE-----
|