SecurityTracker.com
    Home    |    View Topics    |    Search    |    Contact Us    |   

SecurityTracker
Archives


 


Category:   Application (Generic)  >   ntp Vendors:   ntp.org
(FreeBSD Issues Fix) ntp Multiple Bugs Let Remote Users Spoof Messages, Obtain Potentially Sensitive Information, Modify Time, and Deny Service
SecurityTracker Alert ID:  1035708
SecurityTracker URL:  http://securitytracker.com/id/1035708
CVE Reference:   CVE-2016-1547, CVE-2016-1548, CVE-2016-1549, CVE-2016-1550, CVE-2016-1551, CVE-2016-2516, CVE-2016-2517, CVE-2016-2518, CVE-2016-2519   (Links to External Site)
Date:  Apr 29 2016
Impact:   Denial of service via network, Disclosure of system information, Disclosure of user information, Modification of system information, Modification of user information
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   Multiple vulnerabilities were reported in ntp. A remote or remote authenticated user can modify time on the target system. A remote user can cause denial of service conditions on the target system. A remote user can obtain potentially sensitive information on the target system.

A remote user can send specially crafted crypto-NAK packets with a spoofed source address of an existing peer to trigger an error in 'ntp_proto.c' and cause the preemptable client association to be demobilized [CVE-2016-1547].

A remote user can send a spoofed packet with a specially crafted timestamp to cause the target ntpd client to reject future server responses from the spoofed server. As a result, the remote user can modify the time of the target client or cause denial of service conditions on the target client [CVE-2016-1548].

A remote authenticated peer can create an arbitrary number of ephemeral associations to modify the time on the target system [CVE-2016-1549].

A remote user can send a series of specially crafted messages to potentially recover the message digest key [CVE-2016-1550].

A remote user can send specially crafted spoofed packets to a target system that fails to implement martian packet filtering to modify the time on the target system [CVE-2016-1551].

A remote user with knowledge of the controlkey (for ntpq) or the requestkey (for ntpdc) can create a specially crafted session to cause ntpd to crash in certain cases [CVE-2016-2516].

A remote authenticated user with knowledge of the of the controlkey (for ntpq) or the requestkey (for ntpdc) can create a specially crafted session to prevent ntpd from processing authentication requests until the process is restarted [CVE-2016-2517].

A remote authenticated user can send a specially crafted packet to trigger an out-of-bounds memory reference error in the MATCH_ASSOC() function when creating a peer association with hmode > 7 [CVE-2016-2518].

A remote authenticated user can cause a specially crafted data value to be stored by ntpd and then cause ntpd to crash when attempting to read the value via ctl_getitem() [CVE-2016-2519].

Matt Street, Matthew Van Gundy, Stephen Gray, Jonathan Gardner, and others of Cisco ASIG, Yihan Lian (of the Cloud Security Team, Qihoo 360), Miroslav Lichvar of RedHat, Michael Tatarinov (NTP Project Developer Volunteer), and Loganaden Velvindron reported these vulnerabilities.

Impact:   A remote or remote authenticated user can modify time on the target system.

A remote user can cause denial of service conditions.

A remote user can obtain potentially sensitive information on the target system.

Solution:   FreeBSD has issued a fix.

The FreeBSD advisory is available at:

https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc

Vendor URL:  security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc (Links to External Site)
Cause:   Access control error, Input validation error, State error
Underlying OS:  UNIX (FreeBSD)
Underlying OS Comments:  9.3, 10.1, 10.2, 10.3

Message History:   This archive entry is a follow-up to the message listed below.
Apr 28 2016 ntp Multiple Bugs Let Remote Users Spoof Messages, Obtain Potentially Sensitive Information, Modify Time, and Deny Service



 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-16:16.ntp

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

=============================================================================
FreeBSD-SA-16:16.ntp                                        Security Advisory
                                                          The FreeBSD Project

Topic:          Multiple vulnerabilities of ntp

Category:       contrib
Module:         ntp
Announced:      2016-04-29
Credits:        Network Time Foundation and various contributors listed below
Affects:        All supported versions of FreeBSD.
Corrected:      2016-04-27 15:24:33 UTC (stable/10, 10.3-STABLE)
                2016-04-29 08:02:31 UTC (releng/10.3, 10.3-RELEASE-p1)
                2016-04-29 08:02:31 UTC (releng/10.2, 10.2-RELEASE-p15)
                2016-04-29 08:02:31 UTC (releng/10.1, 10.1-RELEASE-p32)
                2016-04-27 15:25:18 UTC (stable/9, 9.3-STABLE)
                2016-04-29 08:02:31 UTC (releng/9.3, 9.3-RELEASE-p40)
CVE Name:       CVE-2016-1547, CVE-2016-1548, CVE-2016-1549, CVE-2016-1550,
                CVE-2016-1551, CVE-2016-2516, CVE-2016-2517, CVE-2016-2518,
                CVE-2016-2519

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 ntpd(8) daemon is an implementation of the Network Time Protocol (NTP)
used to synchronize the time of a computer system to a reference time
source.

II.  Problem Description

Multiple vulnerabilities have been discovered in the NTP suite:

On OSes (FreeBSD not affected) that allows packets claiming to be from
127.0.0.0/8 that arrive over physical network, if ntpd is configured to use
a reference clock, an attacker can inject packets over the network that look
like they are coming from that reference clock.  [CVE-2016-1551, Reported by
Matt Street and others of Cisco ASIG]

If a system is set up to use a trustedkey, and if one is not using the
feature introduced in ntp-4.2.8p6 allowing an optional 4th field in the
ntp.keys file to specify which IPs can serve time, a malicious
authenticated peer -- i.e. one where the attacker knows the private
symmetric key -- can create arbitrarily-many ephemeral associations in
order to win the clock selection of ntpd and modify a victim's clock.
[CVE-2016-1549, Reported by Matthew Van Gundy of Cisco ASIG]

If ntpd was expressly configured to allow for remote configuration (this is
not common), a malicious user who knows the controlkey for ntpq or the
requestkey for ntpdc (if mode7 is expressly enabled) can create a session
with ntpd and if an existing association is unconfigured using the same IP
twice on the unconfig directive line, ntpd will abort. [CVE-2016-2516,
Reported by Yihan Lian of the Cloud Security Team, Qihoo 360]

If ntpd was expressly configured to allow for remote configuration (this is
not common), a malicious user who knows the controlkey for ntpq or the
requestkey for ntpdc (if mode7 is expressly enabled) can create a session
with ntpd and then send a crafted packet to ntpd that will change the value
of the trustedkey, controlkey, or requestkey to a value that will prevent
any subsequent authentication with ntpd until ntpd is restarted.
[CVE-2016-2517, Reported by Yihan Lian of the Cloud Security Team, Qihoo 360]

Using a crafted packet to create a peer association with hmode > 7 causes
the MATCH_ASSOC() lookup to make an out-of-bounds reference. [CVE-2016-2518,
Reported by Yihan Lian of the Cloud Security Team, Qihoo 360]

ntpq and ntpdc can be used to store and retrieve information in ntpd. It is
possible to store a data value that is larger than the size of the buffer
that the ctl_getitem() function of ntpd uses to report the return value.
If the length of the requested data value returned by ctl_getitem() is too
large, the value NULL is returned instead. There are 2 cases where the return
value from ctl_getitem() was not directly checked to make sure it's not NULL,
but there are subsequent INSIST() checks that make sure the return value is
not NULL. There are no data values ordinarily stored in ntpd that would
exceed this buffer length.  But if one has permission to store values and
one stores a value that is "too large", then ntpd will abort if an attempt
is made to read that oversized value. [CVE-2016-2519, Reported by
Yihan Lian of the Cloud Security Team, Qihoo 360]

For ntp-4 versions up to but not including ntp-4.2.8p7, an off-path attacker
can cause a preemptable client association to be demobilized by sending a
crypto NAK packet to a victim client with a spoofed source address of an
existing associated peer. This is true even if authentication is enabled. 
Furthermore, if the attacker keeps sending crypto NAK packets, for example
one every second, the victim never has a chance to reestablish the
association and synchronize time with that legitimate server. For ntp-4.2.8
up to ntp-4.2.8p6 there is less risk because more stringent checks are
performed on incoming packets, but there are still ways to exploit this
vulnerability in versions before ntp-4.2.8p7. [CVE-2016-1547, Reported by
Stephen Gray and Matthew Van Gundy of Cisco ASIG]

It is possible to change the time of an ntpd client or deny service to an
ntpd client by forcing it to change from basic client/server mode to
interleaved symmetric mode. An attacker can spoof a packet from a legitimate
ntpd server with an origin timestamp that matches the peer->dst timestamp
recorded for that server. After making this switch, the client will reject
all future legitimate server responses. It is possible to force the victim
client to move time after the mode has been changed. ntpq gives no
indication that the mode has been switched. [CVE-2016-1548, Reported by
Miroslav Lichvar of RedHat and separately by Jonathan Gardner of
Cisco ASIG]

Packet authentication tests have been performed using memcmp() or possibly
bcmp(), and it is potentially possible for a local or perhaps LAN-based
attacker to send a packet with an authentication payload and indirectly
observe how much of the digest has matched. [CVE-2016-1550, Reported
independently by Loganaden Velvindron, and Matthew Van Gundy and
Stephen Gray of Cisco ASIG]

III. Impact

Malicious remote attackers may be able to break time synchornization,
or cause the ntpd(8) daemon to crash.

IV.  Workaround

No workaround is available, but systems not running ntpd(8) are not
affected.  Network administrators are advised to implement BCP-38,
which helps to reduce risk associated with the attacks.

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.

The ntpd service has to be restarted after the update.  A reboot is
recommended but not required.

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

The ntpd service has to be restarted after the update.  A reboot is
recommended but not required.

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-16:16/ntp.patch
# fetch https://security.FreeBSD.org/patches/SA-16:16/ntp.patch.asc
# gpg --verify ntp.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>.

Restart the applicable daemons, or reboot the system.

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/9/                                                         r298700
releng/9.3/                                                       r298770
stable/10/                                                        r298699
releng/10.1/                                                      r298770
releng/10.2/                                                      r298770
releng/10.3/                                                      r298770
- -------------------------------------------------------------------------

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:http://support.ntp.org/bin/view/Main/SecurityNotice#April_2016_NTP_4_2_8p7_Security>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1547>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1548>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1549>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1550>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1551>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2516>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2517>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2518>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2519>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.1.11 (FreeBSD)
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=nQp/
-----END PGP SIGNATURE-----
_______________________________________________
freebsd-security-notifications@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications
To unsubscribe, send any mail to "freebsd-security-notifications-unsubscribe@freebsd.org"
 
 


Go to the Top of This SecurityTracker Archive Page





Home   |    View Topics   |    Search   |    Contact Us

This web site uses cookies for web analytics. Learn More

Copyright 2019, SecurityGlobal.net LLC