ntp_crypto.c in ntpd in NTP 4.x before 4.2.8p1, when Autokey Authentication is enabled, allows remote attackers to obtain sensitive information from process memory or cause a denial of service (daemon crash) via a packet containing an extension field with an invalid value for the length of its value field.

The remote Redhat Enterprise Linux 5 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - ntp: Stack-based buffer overflow in ntpq and ntpdc allows denial of service or code execution     (CVE-2018-12327)

  - The monlist feature in ntp_request.c in ntpd in NTP before 4.2.7p26 allows remote attackers to cause a     denial of service (traffic amplification) via forged (1) REQ_MON_GETLIST or (2) REQ_MON_GETLIST_1     requests, as exploited in the wild in December 2013. (CVE-2013-5211)

  - An Information Disclosure vulnerability exists in NTP 4.2.7p25 private (mode 6/7) messages via a     GET_RESTRICT control message, which could let a malicious user obtain sensitive information.
    (CVE-2014-5209)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

According to the versions of the ntp packages installed, the EulerOS Virtualization installation on the remote host is affected by the following vulnerabilities :

  - A vulnerability was discovered in the NTP server's     parsing of configuration directives. A remote,     authenticated attacker could cause ntpd to crash by     sending a crafted message.(CVE-2017-6463)

  - ntpd in NTP 4.x before 4.2.8p8, when autokey is     enabled, allows remote attackers to cause a denial of     service (peer-variable clearing and association outage)     by sending (1) a spoofed crypto-NAK packet or (2) a     packet with an incorrect MAC value at a certain     time.(CVE-2016-4955)

  - The ntpq and ntpdc command-line utilities that are part     of ntp package are vulnerable to stack-based buffer     overflow via crafted hostname. Applications using these     vulnerable utilities with an untrusted input may be     potentially exploited, resulting in a crash or     arbitrary code execution under privileges of that     application.(CVE-2018-12327)

  - 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.(CVE-2016-2516)

  - A flaw was found in the way NTP verified trusted keys     during symmetric key authentication. An authenticated     client (A) could use this flaw to modify a packet sent     between a server (B) and a client (C) using a key that     is different from the one known to the client     (A).(CVE-2015-7974)

  - A memory leak flaw was found in ntpd's CRYPTO_ASSOC. If     ntpd was configured to use autokey authentication, an     attacker could send packets to ntpd that would, after     several days of ongoing attack, cause it to run out of     memory.(CVE-2015-7701)

  - An out-of-bounds access flaw was found in the way ntpd     processed certain packets. An authenticated attacker     could use a crafted packet to create a peer association     with hmode of 7 and larger, which could potentially     (although highly unlikely) cause ntpd to     crash.(CVE-2016-2518)

  - A stack-based buffer overflow was found in the way the     NTP autokey protocol was implemented. When an NTP     client decrypted a secret received from an NTP server,     it could cause that client to crash.(CVE-2014-9750)

  - It was found that NTP's :config command could be used     to set the pidfile and driftfile paths without any     restrictions. A remote attacker could use this flaw to     overwrite a file on the file system with a file     containing the pid of the ntpd process (immediately) or     the current estimated drift of the system clock (in     hourly intervals).(CVE-2015-7703)

  - A flaw was found in the way ntpd running on a host with     multiple network interfaces handled certain server     responses. A remote attacker could use this flaw which     would cause ntpd to not synchronize with the     source.(CVE-2016-7429)

  - A flaw was found in the way ntpd implemented the trap     service. A remote attacker could send a specially     crafted packet to cause a null pointer dereference that     will crash ntpd, resulting in a denial of     service.(CVE-2016-9311)

  - It was found that ntp-keygen used a weak method for     generating MD5 keys. This could possibly allow an     attacker to guess generated MD5 keys that could then be     used to spoof an NTP client or server. Note: it is     recommended to regenerate any MD5 keys that had     explicitly been generated with ntp-keygen the default     installation does not contain such keys.(CVE-2014-9294)

  - It was found that when NTP was configured in broadcast     mode, a remote attacker could broadcast packets with     bad authentication to all clients. The clients, upon     receiving the malformed packets, would break the     association with the broadcast server, causing them to     become out of sync over a longer period of     time.(CVE-2015-7979)

  - A flaw was found in the way ntpd calculated the root     delay. A remote attacker could send a specially-crafted     spoofed packet to cause denial of service or in some     special cases even crash.(CVE-2016-7433)

  - It was found that the fix for CVE-2014-9750 was     incomplete: three issues were found in the value length     checks in NTP's ntp_crypto.c, where a packet with     particular autokey operations that contained malicious     data was not always being completely validated. A     remote attacker could use a specially crafted NTP     packet to crash ntpd.(CVE-2015-7691)

  - It was found that ntpd did not correctly implement the     threshold limitation for the '-g' option, which is used     to set the time without any restrictions. A     man-in-the-middle attacker able to intercept NTP     traffic between a connecting client and an NTP server     could use this flaw to force that client to make     multiple steps larger than the panic threshold,     effectively changing the time to an arbitrary value at     any time.(CVE-2015-5300)

  - It was found that ntpd would exit with a segmentation     fault when a statistics type that was not enabled     during compilation (e.g. timingstats) was referenced by     the statistics or filegen configuration     command.(CVE-2015-5195)

  - An off-by-one flaw, leading to a buffer overflow, was     found in cookedprint functionality of ntpq. A specially     crafted NTP packet could potentially cause ntpq to     crash.(CVE-2015-7852)

  - 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.(CVE-2016-4956)

  - A stack-based buffer overflow flaw was found in the way     ntpd processed 'ntpdc reslist' commands that queried     restriction lists with a large amount of entries. A     remote attacker could use this flaw to crash     ntpd.(CVE-2015-7978)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Security Fix(es) :

  - It was found that the fix for CVE-2014-9750 was     incomplete: three issues were found in the value length     checks in NTP's ntp_crypto.c, where a packet with     particular autokey operations that contained malicious     data was not always being completely validated. A remote     attacker could use a specially crafted NTP packet to     crash ntpd. (CVE-2015-7691, CVE-2015-7692,     CVE-2015-7702)

  - A memory leak flaw was found in ntpd's CRYPTO_ASSOC. If     ntpd was configured to use autokey authentication, an     attacker could send packets to ntpd that would, after     several days of ongoing attack, cause it to run out of     memory. (CVE-2015-7701)

  - An off-by-one flaw, leading to a buffer overflow, was     found in cookedprint functionality of ntpq. A specially     crafted NTP packet could potentially cause ntpq to     crash. (CVE-2015-7852)

  - A NULL pointer dereference flaw was found in the way     ntpd processed 'ntpdc reslist' commands that queried     restriction lists with a large amount of entries. A     remote attacker could potentially use this flaw to crash     ntpd. (CVE-2015-7977)

  - A stack-based buffer overflow flaw was found in the way     ntpd processed 'ntpdc reslist' commands that queried     restriction lists with a large amount of entries. A     remote attacker could use this flaw to crash ntpd.
    (CVE-2015-7978)

  - It was found that when NTP was configured in broadcast     mode, a remote attacker could broadcast packets with bad     authentication to all clients. The clients, upon     receiving the malformed packets, would break the     association with the broadcast server, causing them to     become out of sync over a longer period of time.
    (CVE-2015-7979)

  - It was found that ntpd could crash due to an     uninitialized variable when processing malformed     logconfig configuration commands. (CVE-2015-5194)

  - It was found that ntpd would exit with a segmentation     fault when a statistics type that was not enabled during     compilation (e.g. timingstats) was referenced by the     statistics or filegen configuration command.
    (CVE-2015-5195)

  - It was found that NTP's :config command could be used to     set the pidfile and driftfile paths without any     restrictions. A remote attacker could use this flaw to     overwrite a file on the file system with a file     containing the pid of the ntpd process (immediately) or     the current estimated drift of the system clock (in     hourly intervals). (CVE-2015-5196, CVE-2015-7703)

  - It was discovered that the sntp utility could become     unresponsive due to being caught in an infinite loop     when processing a crafted NTP packet. (CVE-2015-5219)

  - A flaw was found in the way NTP verified trusted keys     during symmetric key authentication. An authenticated     client (A) could use this flaw to modify a packet sent     between a server (B) and a client (C) using a key that     is different from the one known to the client (A).
    (CVE-2015-7974)

  - A flaw was found in the way the ntpq client processed     certain incoming packets in a loop in the getresponse()     function. A remote attacker could potentially use this     flaw to crash an ntpq client instance. (CVE-2015-8158)

The CVE-2015-5219 and CVE-2015-7703 issues were discovered by Miroslav Lichvr (Red Hat).

Additional Changes :

Security Fix(es) :

  - It was found that the fix for CVE-2014-9750 was     incomplete: three issues were found in the value length     checks in NTP's ntp_crypto.c, where a packet with     particular autokey operations that contained malicious     data was not always being completely validated. A remote     attacker could use a specially crafted NTP packet to     crash ntpd. (CVE-2015-7691, CVE-2015-7692,     CVE-2015-7702)

  - A memory leak flaw was found in ntpd's CRYPTO_ASSOC. If     ntpd was configured to use autokey authentication, an     attacker could send packets to ntpd that would, after     several days of ongoing attack, cause it to run out of     memory. (CVE-2015-7701)

  - An off-by-one flaw, leading to a buffer overflow, was     found in cookedprint functionality of ntpq. A specially     crafted NTP packet could potentially cause ntpq to     crash. (CVE-2015-7852)

  - A NULL pointer dereference flaw was found in the way     ntpd processed 'ntpdc reslist' commands that queried     restriction lists with a large amount of entries. A     remote attacker could potentially use this flaw to crash     ntpd. (CVE-2015-7977)

  - A stack-based buffer overflow flaw was found in the way     ntpd processed 'ntpdc reslist' commands that queried     restriction lists with a large amount of entries. A     remote attacker could use this flaw to crash ntpd.
    (CVE-2015-7978)

  - It was found that ntpd could crash due to an     uninitialized variable when processing malformed     logconfig configuration commands. (CVE-2015-5194)

  - It was found that ntpd would exit with a segmentation     fault when a statistics type that was not enabled during     compilation (e.g. timingstats) was referenced by the     statistics or filegen configuration command.
    (CVE-2015-5195)

  - It was discovered that the sntp utility could become     unresponsive due to being caught in an infinite loop     when processing a crafted NTP packet. (CVE-2015-5219)

  - It was found that NTP's :config command could be used to     set the pidfile and driftfile paths without any     restrictions. A remote attacker could use this flaw to     overwrite a file on the file system with a file     containing the pid of the ntpd process (immediately) or     the current estimated drift of the system clock (in     hourly intervals). (CVE-2015-7703)

The CVE-2015-5219 and CVE-2015-7703 issues were discovered by Miroslav Lichvr (Red Hat).

It was found that because NTP's access control was based on a source IP address, an attacker could bypass source IP restrictions and send malicious control and configuration packets by spoofing ::1 addresses.
(CVE-2014-9298, CVE-2014-9751)

A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers. (CVE-2015-1799)

A flaw was found in the way the ntp-keygen utility generated MD5 symmetric keys on big-endian systems. An attacker could possibly use this flaw to guess generated MD5 keys, which could then be used to spoof an NTP client or server. (CVE-2015-3405)

A stack-based buffer overflow was found in the way the NTP autokey protocol was implemented. When an NTP client decrypted a secret received from an NTP server, it could cause that client to crash.
(CVE-2014-9297, CVE-2014-9750)

It was found that ntpd did not check whether a Message Authentication Code (MAC) was present in a received packet when ntpd was configured to use symmetric cryptographic keys. A man-in-the-middle attacker could use this flaw to send crafted packets that would be accepted by a client or a peer without the attacker knowing the symmetric key.
(CVE-2015-1798)

Bug fixes :

  - The ntpd service truncated symmetric keys specified in     the key file to 20 bytes. As a consequence, it was     impossible to configure NTP authentication to work with     peers that use longer keys. With this update, the     maximum key length has been changed to 32 bytes.

  - The ntpd service could previously join multicast groups     only when starting, which caused problems if ntpd was     started during system boot before network was     configured. With this update, ntpd attempts to join     multicast groups every time network configuration is     changed.

  - Previously, the ntp-keygen utility used the exponent of     3 when generating RSA keys. Consequently, generating RSA     keys failed when FIPS mode was enabled. With this     update, ntp-keygen has been modified to use the exponent     of 65537, and generating keys in FIPS mode now works as     expected.

  - The ntpd service dropped incoming NTP packets if their     source port was lower than 123 (the NTP port). With this     update, ntpd no longer checks the source port number,     and clients behind NAT are now able to correctly     synchronize with the server.

Enhancements :

  - This update adds support for configurable Differentiated     Services Code Points (DSCP) in NTP packets, simplifying     configuration in large networks where different NTP     implementations or versions are using different DSCP     values.

  - This update adds the ability to configure separate clock     stepping thresholds for each direction (backward and     forward). Use the 'stepback' and 'stepfwd' options to     configure each threshold.

  - Support for nanosecond resolution has been added to the     Structural Health Monitoring (SHM) reference clock.
    Prior to this update, when a Precision Time Protocol     (PTP) hardware clock was used as a time source to     synchronize the system clock, the accuracy of the     synchronization was limited due to the microsecond     resolution of the SHM protocol. The nanosecond extension     in the SHM protocol now allows sub-microsecond     synchronization of the system clock.

Updated ntp packages that fix multiple security issues, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

The Network Time Protocol (NTP) is used to synchronize a computer's time with another referenced time source. These packages include the ntpd service which continuously adjusts system time and utilities used to query and configure the ntpd service.

It was found that because NTP's access control was based on a source IP address, an attacker could bypass source IP restrictions and send malicious control and configuration packets by spoofing ::1 addresses.
(CVE-2014-9298, CVE-2014-9751)

A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers. (CVE-2015-1799)

A flaw was found in the way the ntp-keygen utility generated MD5 symmetric keys on big-endian systems. An attacker could possibly use this flaw to guess generated MD5 keys, which could then be used to spoof an NTP client or server. (CVE-2015-3405)

A stack-based buffer overflow was found in the way the NTP autokey protocol was implemented. When an NTP client decrypted a secret received from an NTP server, it could cause that client to crash.
(CVE-2014-9297, CVE-2014-9750)

It was found that ntpd did not check whether a Message Authentication Code (MAC) was present in a received packet when ntpd was configured to use symmetric cryptographic keys. A man-in-the-middle attacker could use this flaw to send crafted packets that would be accepted by a client or a peer without the attacker knowing the symmetric key.
(CVE-2015-1798)

The CVE-2015-1798 and CVE-2015-1799 issues were discovered by Miroslav Lichvar of Red Hat.

Bug fixes :

* The ntpd service truncated symmetric keys specified in the key file to 20 bytes. As a consequence, it was impossible to configure NTP authentication to work with peers that use longer keys. With this update, the maximum key length has been changed to 32 bytes.
(BZ#1191111)

* The ntpd service could previously join multicast groups only when starting, which caused problems if ntpd was started during system boot before network was configured. With this update, ntpd attempts to join multicast groups every time network configuration is changed.
(BZ#1207014)

* Previously, the ntp-keygen utility used the exponent of 3 when generating RSA keys. Consequently, generating RSA keys failed when FIPS mode was enabled. With this update, ntp-keygen has been modified to use the exponent of 65537, and generating keys in FIPS mode now works as expected. (BZ#1191116)

* The ntpd service dropped incoming NTP packets if their source port was lower than 123 (the NTP port). With this update, ntpd no longer checks the source port number, and clients behind NAT are now able to correctly synchronize with the server. (BZ#1171640)

Enhancements :

* This update adds support for configurable Differentiated Services Code Points (DSCP) in NTP packets, simplifying configuration in large networks where different NTP implementations or versions are using different DSCP values. (BZ#1202828)

* This update adds the ability to configure separate clock stepping thresholds for each direction (backward and forward). Use the 'stepback' and 'stepfwd' options to configure each threshold.
(BZ#1193154)

* Support for nanosecond resolution has been added to the Structural Health Monitoring (SHM) reference clock. Prior to this update, when a Precision Time Protocol (PTP) hardware clock was used as a time source to synchronize the system clock, the accuracy of the synchronization was limited due to the microsecond resolution of the SHM protocol. The nanosecond extension in the SHM protocol now allows sub-microsecond synchronization of the system clock. (BZ#1117702)

All ntp users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements.

The remote Oracle Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2015-2231 advisory.

    - check origin timestamp before accepting KoD RATE packet (CVE-2015-7704)
    - allow only one step larger than panic threshold with -g (CVE-2015-5300)
    - validate lengths of values in extension fields (CVE-2014-9297)
    - drop packets with spoofed source address ::1 (CVE-2014-9298)
    - reject packets without MAC when authentication is enabled (CVE-2015-1798)
    - protect symmetric associations with symmetric key against DoS attack (CVE-2015-1799)
    - fix generation of MD5 keys with ntp-keygen on big-endian systems (CVE-2015-3405)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2015:2231 advisory.

    The Network Time Protocol (NTP) is used to synchronize a computer's time     with another referenced time source. These packages include the ntpd     service which continuously adjusts system time and utilities used to query     and configure the ntpd service.

    It was found that because NTP's access control was based on a source IP     address, an attacker could bypass source IP restrictions and send     malicious control and configuration packets by spoofing ::1 addresses.
    (CVE-2014-9298, CVE-2014-9751)

    A denial of service flaw was found in the way NTP hosts that were peering     with each other authenticated themselves before updating their internal     state variables. An attacker could send packets to one peer host, which     could cascade to other peers, and stop the synchronization process among     the reached peers. (CVE-2015-1799)

    A flaw was found in the way the ntp-keygen utility generated MD5 symmetric     keys on big-endian systems. An attacker could possibly use this flaw to     guess generated MD5 keys, which could then be used to spoof an NTP client     or server. (CVE-2015-3405)

    A stack-based buffer overflow was found in the way the NTP autokey protocol     was implemented. When an NTP client decrypted a secret received from an NTP     server, it could cause that client to crash. (CVE-2014-9297, CVE-2014-9750)

    It was found that ntpd did not check whether a Message Authentication Code     (MAC) was present in a received packet when ntpd was configured to use     symmetric cryptographic keys. A man-in-the-middle attacker could use this     flaw to send crafted packets that would be accepted by a client or a peer     without the attacker knowing the symmetric key. (CVE-2015-1798)

    The CVE-2015-1798 and CVE-2015-1799 issues were discovered by Miroslav     Lichvr of Red Hat.

    Bug fixes:

    * The ntpd service truncated symmetric keys specified in the key file to 20     bytes. As a consequence, it was impossible to configure NTP authentication     to work with peers that use longer keys. With this update, the maximum key     length has been changed to 32 bytes. (BZ#1191111)

    * The ntpd service could previously join multicast groups only when     starting, which caused problems if ntpd was started during system boot     before network was configured. With this update, ntpd attempts to join     multicast groups every time network configuration is changed. (BZ#1207014)

    * Previously, the ntp-keygen utility used the exponent of 3 when generating     RSA keys. Consequently, generating RSA keys failed when FIPS mode was     enabled. With this update, ntp-keygen has been modified to use the exponent     of 65537, and generating keys in FIPS mode now works as expected.
    (BZ#1191116)

    * The ntpd service dropped incoming NTP packets if their source port was     lower than 123 (the NTP port). With this update, ntpd no longer checks the     source port number, and clients behind NAT are now able to correctly     synchronize with the server. (BZ#1171640)

    Enhancements:

    * This update adds support for configurable Differentiated Services Code     Points (DSCP) in NTP packets, simplifying configuration in large networks     where different NTP implementations or versions are using different DSCP     values. (BZ#1202828)

    * This update adds the ability to configure separate clock stepping     thresholds for each direction (backward and forward). Use the stepback     and stepfwd options to configure each threshold. (BZ#1193154)

    * Support for nanosecond resolution has been added to the Structural     Health Monitoring (SHM) reference clock. Prior to this update, when a     Precision Time Protocol (PTP) hardware clock was used as a time source to     synchronize the system clock, the accuracy of the synchronization was     limited due to the microsecond resolution of the SHM protocol. The     nanosecond extension in the SHM protocol now allows sub-microsecond     synchronization of the system clock. (BZ#1117702)

    All ntp users are advised to upgrade to these updated packages, which     contain backported patches to correct these issues and add these     enhancements.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

CVE-2015-7691

The crypto_xmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash) via crafted packets containing particular autokey operations. NOTE: This vulnerability exists due to an incomplete fix for CVE-2014-9750.

CVE-2015-7692 The crypto_xmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash). NOTE: This vulnerability exists due to an incomplete fix for CVE-2014-9750.

CVE-2015-7702 The crypto_xmit function in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash). NOTE: This vulnerability exists due to an incomplete fix for CVE-2014-9750.

Impact

An attacker may be able to craft a packet with particular autokey operations that upon receipt can cause ntpd to stop responding.

Several vulnerabilities were discovered in the Network Time Protocol daemon and utility programs :

  - CVE-2015-5146     A flaw was found in the way ntpd processed certain     remote configuration packets. An attacker could use a     specially crafted package to cause ntpd to crash if :

    - ntpd enabled remote configuration
    - The attacker had the knowledge of the configuration       password

    - The attacker had access to a computer entrusted to       perform remote configuration

      Note that remote configuration is disabled by default       in NTP.

  - CVE-2015-5194     It was found that ntpd could crash due to an     uninitialized variable when processing malformed     logconfig configuration commands.

  - CVE-2015-5195     It was found that ntpd exits with a segmentation fault     when a statistics type that was not enabled during     compilation (e.g. timingstats) is referenced by the     statistics or filegen configuration command.

  - CVE-2015-5219     It was discovered that sntp program would hang in an     infinite loop when a crafted NTP packet was received,     related to the conversion of the precision value in the     packet to double.

  - CVE-2015-5300     It was found that ntpd did not correctly implement the
    -g option :

  Normally, ntpd exits with a message to the system log if the offset   exceeds the panic threshold, which is 1000 s by default. This option   allows the time to be set to any value without restriction; however,   this can happen only once. If the threshold is exceeded after that,   ntpd will exit with a message to the system log. This option can be   used with the -q and -x options.

  ntpd could actually step the clock multiple times by more than the   panic threshold if its clock discipline doesn't have enough time to   reach the sync state and stay there for at least one update. If a   man-in-the-middle attacker can control the NTP traffic since ntpd   was started (or maybe up to 15-30 minutes after that), they can   prevent the client from reaching the sync state and force it to step   its clock by any amount any number of times, which can be used by   attackers to expire certificates, etc.

  This is contrary to what the documentation says. Normally, the   assumption is that an MITM attacker can step the clock more than the   panic threshold only once when ntpd starts and to make a larger   adjustment the attacker has to divide it into multiple smaller   steps, each taking 15 minutes, which is slow.

  - CVE-2015-7691, CVE-2015-7692, CVE-2015-7702     It was found that the fix for CVE-2014-9750 was     incomplete: three issues were found in the value length     checks in ntp_crypto.c, where a packet with particular     autokey operations that contained malicious data was not     always being completely validated. Receipt of these     packets can cause ntpd to crash.

  - CVE-2015-7701     A memory leak flaw was found in ntpd's CRYPTO_ASSOC. If     ntpd is configured to use autokey authentication, an     attacker could send packets to ntpd that would, after     several days of ongoing attack, cause it to run out of     memory.

  - CVE-2015-7703     Miroslav Lichvar of Red Hat found that the :config     command can be used to set the pidfile and driftfile     paths without any restrictions. A remote attacker could     use this flaw to overwrite a file on the file system     with a file containing the pid of the ntpd process     (immediately) or the current estimated drift of the     system clock (in hourly intervals). For example :

  ntpq -c ':config pidfile /tmp/ntp.pid'ntpq -c ':config driftfile   /tmp/ntp.drift'

  In Debian ntpd is configured to drop root privileges, which limits   the impact of this issue.

  - CVE-2015-7704     If ntpd as an NTP client receives a Kiss-of-Death (KoD)     packet from the server to reduce its polling rate, it     doesn't check if the originate timestamp in the reply     matches the transmit timestamp from its request. An     off-path attacker can send a crafted KoD packet to the     client, which will increase the client's polling     interval to a large value and effectively disable     synchronization with the server.

  - CVE-2015-7850     An exploitable denial of service vulnerability exists in     the remote configuration functionality of the Network     Time Protocol. A specially crafted configuration file     could cause an endless loop resulting in a denial of     service. An attacker could provide a malicious     configuration file to trigger this vulnerability.

  - CVE-2015-7852     A potential off by one vulnerability exists in the     cookedprint functionality of ntpq. A specially crafted     buffer could cause a buffer overflow potentially     resulting in null byte being written out of bounds.

  - CVE-2015-7855     It was found that NTP's decodenetnum() would abort with     an assertion failure when processing a mode 6 or mode 7     packet containing an unusually long data value where a     network address was expected. This could allow an     authenticated attacker to crash ntpd.

  - CVE-2015-7871     An error handling logic error exists within ntpd that     manifests due to improper error condition handling     associated with certain crypto-NAK packets. An     unauthenticated, off-path attacker can force ntpd     processes on targeted servers to peer with time sources     of the attacker's choosing by transmitting symmetric     active crypto-NAK packets to ntpd. This attack bypasses     the authentication typically required to establish a     peer association and allows an attacker to make     arbitrary changes to system time.

New ntp packages are available for Slackware 13.0, 13.1, 13.37, 14.0, 14.1, and -current to fix security issues.

The vallen packet value is not validated in several code paths in ntp_crypto.c which can lead to information leakage or a possible crash of ntpd.

Updated ntp packages that fix multiple security issues, several bugs, and add two enhancements are now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

The Network Time Protocol (NTP) is used to synchronize a computer's time with another referenced time source.

It was found that because NTP's access control was based on a source IP address, an attacker could bypass source IP restrictions and send malicious control and configuration packets by spoofing ::1 addresses.
(CVE-2014-9298)

A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers. (CVE-2015-1799)

A flaw was found in the way the ntp-keygen utility generated MD5 symmetric keys on big-endian systems. An attacker could possibly use this flaw to guess generated MD5 keys, which could then be used to spoof an NTP client or server. (CVE-2015-3405)

A stack-based buffer overflow was found in the way the NTP autokey protocol was implemented. When an NTP client decrypted a secret received from an NTP server, it could cause that client to crash.
(CVE-2014-9297)

It was found that ntpd did not check whether a Message Authentication Code (MAC) was present in a received packet when ntpd was configured to use symmetric cryptographic keys. A man-in-the-middle attacker could use this flaw to send crafted packets that would be accepted by a client or a peer without the attacker knowing the symmetric key.
(CVE-2015-1798)

The CVE-2015-1798 and CVE-2015-1799 issues were discovered by Miroslav Lichvar of Red Hat.

Bug fixes :

* The ntpd daemon truncated symmetric keys specified in the key file to 20 bytes. As a consequence, it was impossible to configure NTP authentication to work with peers that use longer keys. The maximum length of keys has now been changed to 32 bytes. (BZ#1053551)

* The ntp-keygen utility used the exponent of 3 when generating RSA keys, and generating RSA keys failed when FIPS mode was enabled.
ntp-keygen has been modified to use the exponent of 65537, and generating keys in FIPS mode now works as expected. (BZ#1184421)

* The ntpd daemon included a root delay when calculating its root dispersion. Consequently, the NTP server reported larger root dispersion than it should have and clients could reject the source when its distance reached the maximum synchronization distance (1.5 seconds by default). Calculation of root dispersion has been fixed, the root dispersion is now reported correctly, and clients no longer reject the server due to a large synchronization distance.
(BZ#1045376)

* The ntpd daemon dropped incoming NTP packets if their source port was lower than 123 (the NTP port). Clients behind Network Address Translation (NAT) were unable to synchronize with the server if their source port was translated to ports below 123. With this update, ntpd no longer checks the source port number. (BZ#1171630)

Enhancements :

* This update introduces configurable access of memory segments used for Shared Memory Driver (SHM) reference clocks. Previously, only the first two memory segments were created with owner-only access, allowing just two SHM reference clocks to be used securely on a system. Now, the owner-only access to SHM is configurable with the 'mode' option, and it is therefore possible to use more SHM reference clocks securely. (BZ#1122015)

* Support for nanosecond resolution has been added to the SHM reference clock. Prior to this update, when a Precision Time Protocol (PTP) hardware clock was used as a time source to synchronize the system clock (for example, with the timemaster service from the linuxptp package), the accuracy of the synchronization was limited due to the microsecond resolution of the SHM protocol. The nanosecond extension in the SHM protocol now enables sub-microsecond synchronization of the system clock. (BZ#1117704)

The remote Redhat Enterprise Linux 6 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2015:1459 advisory.

    The Network Time Protocol (NTP) is used to synchronize a computer's time     with another referenced time source.

    It was found that because NTP's access control was based on a source IP     address, an attacker could bypass source IP restrictions and send malicious     control and configuration packets by spoofing ::1 addresses.
    (CVE-2014-9298)

    A denial of service flaw was found in the way NTP hosts that were peering     with each other authenticated themselves before updating their internal     state variables. An attacker could send packets to one peer host, which     could cascade to other peers, and stop the synchronization process among     the reached peers. (CVE-2015-1799)

    A flaw was found in the way the ntp-keygen utility generated MD5 symmetric     keys on big-endian systems. An attacker could possibly use this flaw to     guess generated MD5 keys, which could then be used to spoof an NTP client     or server. (CVE-2015-3405)

    A stack-based buffer overflow was found in the way the NTP autokey protocol     was implemented. When an NTP client decrypted a secret received from an NTP     server, it could cause that client to crash. (CVE-2014-9297)

    It was found that ntpd did not check whether a Message Authentication Code     (MAC) was present in a received packet when ntpd was configured to use     symmetric cryptographic keys. A man-in-the-middle attacker could use this     flaw to send crafted packets that would be accepted by a client or a peer     without the attacker knowing the symmetric key. (CVE-2015-1798)

    The CVE-2015-1798 and CVE-2015-1799 issues were discovered by Miroslav     Lichvr of Red Hat.

    Bug fixes:

    * The ntpd daemon truncated symmetric keys specified in the key file to 20     bytes. As a consequence, it was impossible to configure NTP authentication     to work with peers that use longer keys. The maximum length of keys has now     been changed to 32 bytes. (BZ#1053551)

    * The ntp-keygen utility used the exponent of 3 when generating RSA keys,     and generating RSA keys failed when FIPS mode was enabled. ntp-keygen has     been modified to use the exponent of 65537, and generating keys in FIPS     mode now works as expected. (BZ#1184421)

    * The ntpd daemon included a root delay when calculating its root     dispersion. Consequently, the NTP server reported larger root dispersion     than it should have and clients could reject the source when its distance     reached the maximum synchronization distance (1.5 seconds by default).
    Calculation of root dispersion has been fixed, the root dispersion is now     reported correctly, and clients no longer reject the server due to a large     synchronization distance. (BZ#1045376)

    * The ntpd daemon dropped incoming NTP packets if their source port was     lower than 123 (the NTP port). Clients behind Network Address Translation     (NAT) were unable to synchronize with the server if their source port was     translated to ports below 123. With this update, ntpd no longer checks the     source port number. (BZ#1171630)

    Enhancements:

    * This update introduces configurable access of memory segments used for     Shared Memory Driver (SHM) reference clocks. Previously, only the first two     memory segments were created with owner-only access, allowing just two SHM     reference clocks to be used securely on a system. Now, the owner-only     access to SHM is configurable with the mode option, and it is therefore     possible to use more SHM reference clocks securely. (BZ#1122015)

    * Support for nanosecond resolution has been added to the SHM reference     clock. Prior to this update, when a Precision Time Protocol (PTP) hardware     clock was used as a time source to synchronize the system clock (for     example, with the timemaster service from the linuxptp package), the     accuracy of the synchronization was limited due to the microsecond     resolution of the SHM protocol. The nanosecond extension in the SHM     protocol now enables sub-microsecond synchronization of the system clock.
    (BZ#1117704)

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of the remote NTP server is 4.x prior to 4.2.8p1. It is, therefore, affected by the following vulnerabilities :

  - A security weakness exists due to the config_auth()     function improperly generating default keys when no     authentication key is defined in the ntp.conf file.
    Key size is limited to 31 bits and the insecure     ntp_random() function is used, resulting in     cryptographically-weak keys with insufficient entropy. A     remote attacker can exploit this to defeat cryptographic     protection mechanisms via a brute-force attack.
    (CVE-2014-9293)

  - A security weakness exists due the use of a weak seed to     prepare a random number generator used to generate     symmetric keys. This allows a remote attacker to defeat     cryptographic protection mechanisms via a brute-force     attack. (CVE-2014-9294)

  - Multiple stack-based buffer overflow conditions exist     due to improper validation of user-supplied input when     handling packets in the crypto_recv(), ctl_putdata(),     and configure() functions when using autokey     authentication. A remote attacker can exploit this, via     a specially crafted packet, to cause a denial of service     condition or the execution of arbitrary code.
    (CVE-2014-9295)

  - A unspecified vulnerability exists due to missing return     statements in the receive() function, resulting in     continued processing even when an authentication error     is encountered. This allows a remote attacker, via     specially crafted packets, to trigger unintended     association changes. (CVE-2014-9296)

  - An information disclosure vulnerability exists due to     improper validation of the 'vallen' value in extension     fields in ntp_crypto.c. A remote attacker can exploit     this to disclose sensitive information. (CVE-2014-9750)

  - A security bypass vulnerability exists due to a failure     to restrict ::1 source addresses on IPv6 interfaces. A     remote attacker can exploit this to bypass configured     ACLs based on ::1. (CVE-2014-9751)

Note that CVE-2014-9750 and CVE-2014-9751 supersede the discontinued identifiers CVE-2014-9297 and CVE-2014-9298, which were originally cited in the vendor advisory.

Several vulnerabilities were discovered in the ntp package, an implementation of the Network Time Protocol. The Common Vulnerabilities and Exposures project identifies the following problems :

  - CVE-2014-9750     Stephen Roettger of the Google Security Team, Sebastian     Krahmer of the SUSE Security Team and Harlan Stenn of     Network Time Foundation discovered that the length value     in extension fields is not properly validated in several     code paths in ntp_crypto.c, which could lead to     information leakage or denial of service (ntpd crash).

  - CVE-2014-9751     Stephen Roettger of the Google Security Team reported     that ACLs based on IPv6 ::1 addresses can be bypassed.

ID	Name	Product	Family	Severity
198530	RHEL 5 : ntp (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	critical
125009	EulerOS Virtualization 3.0.1.0 : ntp (EulerOS-SA-2019-1556)	Nessus	Huawei Local Security Checks	critical
95850	Scientific Linux Security Update : ntp on SL7.x x86_64 (20161103)	Nessus	Scientific Linux Local Security Checks	high
91539	Scientific Linux Security Update : ntp on SL6.x i386/x86_64 (20160510)	Nessus	Scientific Linux Local Security Checks	high
87564	Scientific Linux Security Update : ntp on SL7.x x86_64 (20151119)	Nessus	Scientific Linux Local Security Checks	high
87143	CentOS 7 : ntp (CESA-2015:2231)	Nessus	CentOS Local Security Checks	high
87030	Oracle Linux 7 : ntp (ELSA-2015-2231)	Nessus	Oracle Linux Local Security Checks	high
86975	RHEL 7 : ntp (RHSA-2015:2231)	Nessus	Red Hat Local Security Checks	high
86773	F5 Networks BIG-IP : NTP vulnerabilities (K17530)	Nessus	F5 Networks Local Security Checks	high
86682	Debian DSA-3388-1 : ntp - security update	Nessus	Debian Local Security Checks	critical
86664	Slackware 13.0 / 13.1 / 13.37 / 14.0 / 14.1 / current : ntp (SSA:2015-302-03)	Nessus	Slackware Local Security Checks	critical
85949	F5 Networks BIG-IP : NTP vulnerability (SOL16392)	Nessus	F5 Networks Local Security Checks	medium
85025	CentOS 6 : ntp (CESA-2015:1459)	Nessus	CentOS Local Security Checks	high
84951	RHEL 6 : ntp (RHSA-2015:1459)	Nessus	Red Hat Local Security Checks	high
81981	Network Time Protocol Daemon (ntpd) 4.x < 4.2.8p1 Multiple Vulnerabilities	Nessus	Misc.	critical
81189	Debian DSA-3154-1 : ntp - security update	Nessus	Debian Local Security Checks	medium

Detections

Analytics

CVE-2014-9750

critical

Tenable Plugins

critical

critical

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critical

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medium

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medium