FreeBSD Security Advisory FreeBSD-SA-16:09.ntp

Fabricante: FreeBSD
Fecha: 27/01/2016
Identificador: FreeBSD-SA-16:09.ntp
FreeBSD Security Advisory FreeBSD-SA-16:09.ntp
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:09.ntp Security Advisory The FreeBSD Project Topic: Multiple vulnerabilities of ntp Category: contrib Module: ntp Announced: 2016-01-27 Credits: Cisco ASIG / Network Time Foundation Affects: All supported versions of FreeBSD. Corrected: 2016-01-22 15:55:21 UTC (stable/10, 10.2-STABLE) 2016-01-27 07:41:31 UTC (releng/10.2, 10.2-RELEASE-p11) 2016-01-27 07:41:31 UTC (releng/10.1, 10.1-RELEASE-p28) 2016-01-22 15:56:35 UTC (stable/9, 9.3-STABLE) 2016-01-27 07:42:11 UTC (releng/9.3, 9.3-RELEASE-p35) CVE Name: CVE-2015-7973, CVE-2015-7974, CVE-2015-7975, CVE-2015-7976, CVE-2015-7977, CVE-2015-7978, CVE-2015-7979, CVE-2015-8138, CVE-2015-8139, CVE-2015-8140, CVE-2015-8158 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . 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 ntp 4.2.8p5: Potential Infinite Loop in ntpq. [CVE-2015-8158] A logic error would allow packets with an origin timestamp of zero to bypass this check whenever there is not an outstanding request to the server. [CVE-2015-8138] Off-path Denial of Service (DoS) attack on authenticated broadcast mode. [CVE-2015-7979] Stack exhaustion in recursive traversal of restriction list. [CVE-2015-7978] reslist NULL pointer dereference. [CVE-2015-7977] ntpq saveconfig command allows dangerous characters in filenames. [CVE-2015-7976] nextvar() missing length check. [CVE-2015-7975] Skeleton Key: Missing key check allows impersonation between authenticated peers. [CVE-2015-7974] Deja Vu: Replay attack on authenticated broadcast mode. [CVE-2015-7973] ntpq vulnerable to replay attacks. [CVE-2015-8140] Origin Leak: ntpq and ntpdc, disclose origin. [CVE-2015-8139] III. Impact A malicious NTP server, or an attacker who can conduct MITM attack by intercepting NTP query traffic, may be able to cause a ntpq client to infinitely loop. [CVE-2015-8158] A malicious NTP server, or an attacker who can conduct MITM attack by intercepting NTP query traffic, may be able to prevent a ntpd(8) daemon to distinguish between legitimate peer responses from forgeries. This can partially be mitigated by configuring multiple time sources. [CVE-2015-8138] An off-path attacker who can send broadcast packets with bad authentication (wrong key, mismatched key, incorrect MAC, etc) to broadcast clients can cause these clients to tear down associations. [CVE-2015-7979] An attacker who can send unauthenticated 'reslist' command to a NTP server may cause it to crash, resulting in a denial of service condition due to stack exhaustion [CVE-2015-7978] or a NULL pointer dereference [CVE-2015-7977]. An attacker who can send 'modify' requests to a NTP server may be able to create file that contain dangerous characters in their name, which could cause dangerous behavior in a later shell invocation. [CVE-2015-7976] A remote attacker may be able to crash a ntpq client. [CVE-2015-7975] A malicious server which holds a trusted key may be able to impersonate other trusted servers in an authenticated configuration. [CVE-2015-7974] A man-in-the-middle attacker or a malicious participant that has the same trusted keys as the victim can replay time packets if the NTP network is configured for broadcast operations. [CVE-2015-7973] The ntpq protocol is vulnerable to replay attacks which may be used to e.g. re-establish an association to malicious server. [CVE-2015-8140] An attacker who can intercept NTP traffic can easily forge live server responses. [CVE-2015-8139] 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-16:09/ntp.patch # fetch https://security.FreeBSD.org/patches/SA-16:09/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 . 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/ r294570 releng/9.3/ r294905 stable/10/ r294569 releng/10.1/ r294904 releng/10.2/ r294904 - ------------------------------------------------------------------------- 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: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.8 (FreeBSD) iQIcBAEBCgAGBQJWqHmfAAoJEO1n7NZdz2rnt9cP/2EtdEPX/oBJXKFWqQv5cwvY C4gmlK5MZok2an330XMPl0RO2RplsIw4Lo4BuUh7HPKhVa5loYasabKrULQ+4Pgv z9INxDTDO8iooHeTeNe/VAb5YcKFrD7sqajdc0cY11rLEw1o53IuULz9wZnczAe/ KnHDNUyYaSU2Ep+c3+ADSJqOk3ffhsGDS+0byoOBcUN+66MnBg19/rKomiN5a7Nt XSseoQgYISU8aaJDvPlGoaN/Xm5fnFZaKFlJ4y7h51sYYep0qgjQx+Gdakk0vNbh CwsjpBKqDpFpBcSgdEC/bYHnNpYUTJB/tPmG3YDO5jMWQISKGrrnuMYeh+7PjTDS vCrneztpVBscLG4ZKSlfmhpZ/Jfy31YPXm5P/w8NuA05i13K06P4gG5PKNyUMgsk AZQ4Vg8YlyS0Ci4ufdc+AIQI35QMrKvfecJVu49+sNhUA4PpTe7coEU9dks3Dtaw g2QbfnsEWzJ6RBJcw7aQDSgRoqrVQgMB8IIota+aMzeVurgyFxPm9LASk2RYjhmC Ep283cc+HPUnihKBZTwwkw5iznbmpyRYlPghEc7slgOZCbk9pefnsCMOZAqRW9fZ DUpt+HvZD5BKB4kCAUMIvKGS91cyBFaNcdJhlB8uUx2aP2UJmuzldk+x9K74wWGK lnP0IazzXnWFobfwr+qT =0ZhD -----END PGP SIGNATURE-----