CVE-2016-2516

NTP before 4.2.8p7 and 4.3.x before 4.3.92, when mode7 is enabled, allows remote attackers to cause a denial of service (ntpd abort) by using the same IP address multiple times in an unconfig directive.

Updated ntp packages fix security vulnerabilities:

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).

An exploitable vulnerability exists in the message authentication functionality of Network Time Protocol libntp. An attacker can send a series of crafted messages to attempt to recover the message digest key (CVE-2016-1550).

If ntpd was expressly configured to allow for remote configuration, 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).

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).

Note that CVE-2016-2516, as well as other known but unfixed vulnerabilities in ntpd, are also mitigated by not allowing remote configuration, which is the default in Mageia.

These are all security issues fixed in the ntp-4.2.8p9-1.1 package on the GA media of openSUSE Tumbleweed.

This update for ntp to 4.2.8p7 fixes the following issues:

• CVE-2016-1547, bsc#977459: Validate crypto-NAKs, AKA: CRYPTO-NAK DoS.
• CVE-2016-1548, bsc#977461: Interleave-pivot
• CVE-2016-1549, bsc#977451: Sybil vulnerability: ephemeral association attack.
• CVE-2016-1550, bsc#977464: Improve NTP security against buffer comparison timing attacks.
• CVE-2016-1551, bsc#977450: Refclock impersonation vulnerability
• CVE-2016-2516, bsc#977452: Duplicate IPs on unconfig directives will cause an assertion botch in ntpd.
• CVE-2016-2517, bsc#977455: remote configuration trustedkey/ requestkey/controlkey values are not properly validated.
• CVE-2016-2518, bsc#977457: Crafted addpeer with hmode > 7 causes array wraparound with MATCH_ASSOC.
• CVE-2016-2519, bsc#977458: ctl_getitem() return value not always checked.
• This update also improves the fixes for: CVE-2015-7704, CVE-2015-7705, CVE-2015-7974

Bugs fixed:

• Restrict the parser in the startup script to the first occurrance of 'keys' and 'controlkey' in ntp.conf (bsc#957226).

This update for ntp to 4.2.8p7 fixes the following issues:

• CVE-2016-1547, bsc#977459: Validate crypto-NAKs, AKA: CRYPTO-NAK DoS.
• CVE-2016-1548, bsc#977461: Interleave-pivot
• CVE-2016-1549, bsc#977451: Sybil vulnerability: ephemeral association attack.
• CVE-2016-1550, bsc#977464: Improve NTP security against buffer comparison timing attacks.
• CVE-2016-1551, bsc#977450: Refclock impersonation vulnerability
• CVE-2016-2516, bsc#977452: Duplicate IPs on unconfig directives will cause an assertion botch in ntpd.
• CVE-2016-2517, bsc#977455: remote configuration trustedkey/ requestkey/controlkey values are not properly validated.
• CVE-2016-2518, bsc#977457: Crafted addpeer with hmode > 7 causes array wraparound with MATCH_ASSOC.
• CVE-2016-2519, bsc#977458: ctl_getitem() return value not always checked.
• This update also improves the fixes for: CVE-2015-7704, CVE-2015-7705, CVE-2015-7974

Bugs fixed:

• Restrict the parser in the startup script to the first occurrance of 'keys' and 'controlkey' in ntp.conf (bsc#957226).

This update for ntp fixes the following issues:

• Separate the creation of ntp.keys and key #1 in it to avoid problems when upgrading installations that have the file, but no key #1, which is needed e.g. by 'rcntp addserver'.

• Update to 4.2.8p7 (bsc#977446):

  • CVE-2016-1547, bsc#977459: Validate crypto-NAKs, AKA: CRYPTO-NAK DoS.
  • CVE-2016-1548, bsc#977461: Interleave-pivot
  • CVE-2016-1549, bsc#977451: Sybil vulnerability: ephemeral association attack.
  • CVE-2016-1550, bsc#977464: Improve NTP security against buffer comparison timing attacks.
  • CVE-2016-1551, bsc#977450: Refclock impersonation vulnerability
  • CVE-2016-2516, bsc#977452: Duplicate IPs on unconfig directives will cause an assertion botch in ntpd.
  • CVE-2016-2517, bsc#977455: remote configuration trustedkey/ requestkey/controlkey values are not properly validated.
  • CVE-2016-2518, bsc#977457: Crafted addpeer with hmode > 7 causes array wraparound with MATCH_ASSOC.
  • CVE-2016-2519, bsc#977458: ctl_getitem() return value not always checked.
  • integrate ntp-fork.patch
  • Improve the fixes for: CVE-2015-7704, CVE-2015-7705, CVE-2015-7974

• Restrict the parser in the startup script to the first occurrance of 'keys' and 'controlkey' in ntp.conf (bsc#957226).

ntp was updated to version 4.2.8p8 to fix 17 security issues.

These security issues were fixed:

• CVE-2016-4956: Broadcast interleave (bsc#982068).
• CVE-2016-2518: Crafted addpeer with hmode > 7 causes array wraparound with MATCH_ASSOC (bsc#977457).
• CVE-2016-2519: ctl_getitem() return value not always checked (bsc#977458).
• CVE-2016-4954: Processing spoofed server packets (bsc#982066).
• CVE-2016-4955: Autokey association reset (bsc#982067).
• CVE-2015-7974: NTP did not verify peer associations of symmetric keys when authenticating packets, which might allowed remote attackers to conduct impersonation attacks via an arbitrary trusted key, aka a 'skeleton key (bsc#962960).
• CVE-2016-4957: CRYPTO_NAK crash (bsc#982064).
• CVE-2016-2516: Duplicate IPs on unconfig directives will cause an assertion botch (bsc#977452).
• CVE-2016-2517: Remote configuration trustedkey/requestkey values are not properly validated (bsc#977455).
• CVE-2016-4953: Bad authentication demobilizes ephemeral associations (bsc#982065).
• CVE-2016-1547: CRYPTO-NAK DoS (bsc#977459).
• CVE-2016-1551: Refclock impersonation vulnerability, AKA: refclock-peering (bsc#977450).
• CVE-2016-1550: Improve NTP security against buffer comparison timing attacks, authdecrypt-timing, AKA: authdecrypt-timing (bsc#977464).
• CVE-2016-1548: Interleave-pivot - MITIGATION ONLY (bsc#977461).
• CVE-2016-1549: Sybil vulnerability: ephemeral association attack, AKA: ntp-sybil - MITIGATION ONLY (bsc#977451).

This release also contained improved patches for CVE-2015-7704, CVE-2015-7705, CVE-2015-7974.

These non-security issues were fixed:

• bsc#979302: Change the process name of the forking DNS worker process to avoid the impression that ntpd is started twice.
• bsc#981422: Don't ignore SIGCHILD because it breaks wait().
• bsc#979981: ntp-wait does not accept fractional seconds, so use 1 instead of 0.2 in ntp-wait.service.
• Separate the creation of ntp.keys and key #1 in it to avoid problems when upgrading installations that have the file, but no key #1, which is needed e.g. by 'rcntp addserver'.
• bsc#957226: Restrict the parser in the startup script to the first occurrance of 'keys' and 'controlkey' in ntp.conf.

Aanchal Malhotra discovered that NTP incorrectly handled authenticated broadcast mode. A remote attacker could use this issue to perform a replay attack. (CVE-2015-7973)

Matt Street discovered that NTP incorrectly verified peer associations of symmetric keys. A remote attacker could use this issue to perform an impersonation attack. (CVE-2015-7974)

Jonathan Gardner discovered that the NTP ntpq utility incorrectly handled memory. An attacker could possibly use this issue to cause ntpq to crash, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS. (CVE-2015-7975)

Jonathan Gardner discovered that the NTP ntpq utility incorrectly handled dangerous characters in filenames. An attacker could possibly use this issue to overwrite arbitrary files. (CVE-2015-7976)

Stephen Gray discovered that NTP incorrectly handled large restrict lists. An attacker could use this issue to cause NTP to crash, resulting in a denial of service. (CVE-2015-7977, CVE-2015-7978)

Aanchal Malhotra discovered that NTP incorrectly handled authenticated broadcast mode. A remote attacker could use this issue to cause NTP to crash, resulting in a denial of service. (CVE-2015-7979)

Jonathan Gardner discovered that NTP incorrectly handled origin timestamp checks. A remote attacker could use this issue to spoof peer servers. (CVE-2015-8138)

Jonathan Gardner discovered that the NTP ntpq utility did not properly handle certain incorrect values. An attacker could possibly use this issue to cause ntpq to hang, resulting in a denial of service. (CVE-2015-8158)

It was discovered that the NTP cronjob incorrectly cleaned up the statistics directory. A local attacker could possibly use this to escalate privileges. (CVE-2016-0727)

Stephen Gray and Matthew Van Gundy discovered that NTP incorrectly validated crypto-NAKs. A remote attacker could possibly use this issue to prevent clients from synchronizing. (CVE-2016-1547)

Miroslav Lichvar and Jonathan Gardner discovered that NTP incorrectly handled switching to interleaved symmetric mode. A remote attacker could possibly use this issue to prevent clients from synchronizing. (CVE-2016-1548)

Matthew Van Gundy, Stephen Gray and Loganaden Velvindron discovered that NTP incorrectly handled message authentication. A remote attacker could possibly use this issue to recover the message digest key. (CVE-2016-1550)

Yihan Lian discovered that NTP incorrectly handled duplicate IPs on unconfig directives. An authenticated remote attacker could possibly use this issue to cause NTP to crash, resulting in a denial of service. (CVE-2016-2516)

Yihan Lian discovered that NTP incorrectly handled certail peer associations. A remote attacker could possibly use this issue to cause NTP to crash, resulting in a denial of service. (CVE-2016-2518)

Jakub Prokes discovered that NTP incorrectly handled certain spoofed packets. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2016-4954)

Miroslav Lichvar discovered that NTP incorrectly handled certain packets when autokey is enabled. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2016-4955)

Miroslav Lichvar discovered that NTP incorrectly handled certain spoofed broadcast packets. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2016-4956)

In the default installation, attackers would be isolated by the NTP AppArmor profile.