CVE-2016-4956

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (interleaved-mode transition and time change) via a spoofed broadcast packet. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-1548.

ntpq and ntpdc disclose the origin timestamp to unauthenticated clients, which may allow an attacker to impersonate a legitimate peer (CVE-2015-8139).

An attacker who is able to spoof packets with correct origin timestamps from enough servers before the expected response packets arrive at the target machine can affect some peer variables and, for example, cause a false leap indication to be set (CVE-2016-4954).

An attacker who is able to spoof a packet with a correct origin timestamp before the expected response packet arrives at the target machine can send a CRYPTO_NAK or a bad MAC and cause the association's peer variables to be cleared. If this can be done often enough, it will prevent that association from working (CVE-2016-4955).

The fix for CVE-2016-1548 does not cover broadcast associations, so broadcast clients can be triggered to flip into interleave mode (CVE-2016-4956).

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

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

These security issues were fixed:

• CVE-2016-4953: Bad authentication demobilizes ephemeral associations (bsc#982065).
• CVE-2016-4954: Processing spoofed server packets (bsc#982066).
• CVE-2016-4955: Autokey association reset (bsc#982067).
• CVE-2016-4956: Broadcast interleave (bsc#982068).
• CVE-2016-4957: CRYPTO_NAK crash (bsc#982064).

These non-security issues were fixed:

• Keep the parent process alive until the daemon has finished initialisation, to make sure that the PID file exists when the parent returns.
• 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'.

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.

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

These security issues were fixed:

• CVE-2016-4953: Bad authentication demobilizes ephemeral associations (bsc#982065).
• CVE-2016-4954: Processing spoofed server packets (bsc#982066).
• CVE-2016-4955: Autokey association reset (bsc#982067).
• CVE-2016-4956: Broadcast interleave (bsc#982068).
• CVE-2016-4957: CRYPTO_NAK crash (bsc#982064).

These non-security issues were fixed:

• Keep the parent process alive until the daemon has finished initialisation, to make sure that the PID file exists when the parent returns.
• 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().
• 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'.

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

These security issues were fixed:

• CVE-2016-4953: Bad authentication demobilizes ephemeral associations (bsc#982065).
• CVE-2016-4954: Processing spoofed server packets (bsc#982066).
• CVE-2016-4955: Autokey association reset (bsc#982067).
• CVE-2016-4956: Broadcast interleave (bsc#982068).
• CVE-2016-4957: CRYPTO_NAK crash (bsc#982064).

These non-security issues were fixed:

• Keep the parent process alive until the daemon has finished initialisation, to make sure that the PID file exists when the parent returns.
• 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().

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.