The remote NewStart CGSL host, running version MAIN 6.02, has chrony packages installed that are affected by multiple vulnerabilities:

  - Multiple integer overflows in pktlength.c in Chrony before 1.29 allow remote attackers to cause a denial     of service (crash) via a crafted (1) REQ_SUBNETS_ACCESSED or (2) REQ_CLIENT_ACCESSES command request to     the PKL_CommandLength function or crafted (3) RPY_SUBNETS_ACCESSED, (4) RPY_CLIENT_ACCESSES, (5)     RPY_CLIENT_ACCESSES_BY_INDEX, or (6) RPY_MANUAL_LIST command reply to the PKL_ReplyLength function, which     triggers an out-of-bounds read or buffer overflow. NOTE: versions 1.27 and 1.28 do not require     authentication to exploit. (CVE-2012-4502)

  - cmdmon.c in Chrony before 1.29 allows remote attackers to obtain potentially sensitive information from     stack memory via vectors related to (1) an invalid subnet in a RPY_SUBNETS_ACCESSED command to the     handle_subnets_accessed function or (2) a RPY_CLIENT_ACCESSES command to the handle_client_accesses     function when client logging is disabled, which causes uninitialized data to be included in a reply.
    (CVE-2012-4503)

  - Chrony before 1.29.1 has traffic amplification in cmdmon protocol (CVE-2014-0021)

  - Heap-based buffer overflow in chrony before 1.31.1 allows remote authenticated users to cause a denial of     service (chronyd crash) or possibly execute arbitrary code by configuring the (1) NTP or (2) cmdmon access     with a subnet size that is indivisible by four and an address with a nonzero bit in the subnet remainder.
    (CVE-2015-1821)

  - chrony before 1.31.1 does not initialize the last next pointer when saving unacknowledged replies to     command requests, which allows remote authenticated users to cause a denial of service (uninitialized     pointer dereference and daemon crash) or possibly execute arbitrary code via a large number of command     requests. (CVE-2015-1822)

  - chrony before 1.31.1 does not properly protect state variables in authenticated symmetric NTP     associations, which allows remote attackers with knowledge of NTP peering to cause a denial of service     (inability to synchronize) via random timestamps in crafted NTP data packets. (CVE-2015-1853)

  - chrony before 1.31.2 and 2.x before 2.2.1 do not verify peer associations of symmetric keys when     authenticating packets, which might allow remote attackers to conduct impersonation attacks via an     arbitrary trusted key, aka a skeleton key. (CVE-2016-1567)

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

The remote NewStart CGSL host, running version MAIN 6.06 (SP), has chrony packages installed that are affected by multiple vulnerabilities:

  - chrony before 1.31.2 and 2.x before 2.2.1 do not verify peer associations of symmetric keys when     authenticating packets, which might allow remote attackers to conduct impersonation attacks via an     arbitrary trusted key, aka a skeleton key. (CVE-2016-1567)

  - The read_from_cmd_socket function in cmdmon.c in chronyd in Chrony before 1.23.1, and 1.24-pre1, allows     remote attackers to cause a denial of service (CPU and bandwidth consumption) by sending a spoofed cmdmon     packet that triggers a continuous exchange of NOHOSTACCESS messages between two daemons, a related issue     to CVE-2009-3563. (CVE-2010-0292)

  - The client logging functionality in chronyd in Chrony before 1.23.1 does not restrict the amount of memory     used for storage of client information, which allows remote attackers to cause a denial of service (memory     consumption) via spoofed (1) NTP or (2) cmdmon packets. (CVE-2010-0293)

  - chronyd in Chrony before 1.23.1, and possibly 1.24-pre1, generates a syslog message for each unauthorized     cmdmon packet, which allows remote attackers to cause a denial of service (disk consumption) via a large     number of invalid packets. (CVE-2010-0294)

  - Multiple integer overflows in pktlength.c in Chrony before 1.29 allow remote attackers to cause a denial     of service (crash) via a crafted (1) REQ_SUBNETS_ACCESSED or (2) REQ_CLIENT_ACCESSES command request to     the PKL_CommandLength function or crafted (3) RPY_SUBNETS_ACCESSED, (4) RPY_CLIENT_ACCESSES, (5)     RPY_CLIENT_ACCESSES_BY_INDEX, or (6) RPY_MANUAL_LIST command reply to the PKL_ReplyLength function, which     triggers an out-of-bounds read or buffer overflow. NOTE: versions 1.27 and 1.28 do not require     authentication to exploit. (CVE-2012-4502)

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

CVE-2015-1853 :

Protect authenticated symmetric NTP associations against DoS attacks.

An attacker knowing that NTP hosts A and B are peering with each other (symmetric association) can send a packet with random timestamps to host A with source address of B which will set the NTP state variables on A to the values sent by the attacker. Host A will then send on its next poll to B a packet with originate timestamp that doesn't match the transmit timestamp of B and the packet will be dropped. If the attacker does this periodically for both hosts, they won't be able to synchronize to each other. It is a denial of service attack.

According to [1], NTP authentication is supposed to protect symmetric associations against this attack, but in the NTPv3 (RFC 1305) and NTPv4 (RFC 5905) specifications the state variables are updated before the authentication check is performed, which means the association is vulnerable to the attack even when authentication is enabled.

To fix this problem, save the originate and local timestamps only when the authentication check (test5) passed.

[1] https://www.eecis.udel.edu/~mills/onwire.html

CVE-2015-1821 :

Fix access configuration with subnet size indivisible by 4.

When NTP or cmdmon access was configured (from chrony.conf or via authenticated cmdmon) with a subnet size that is indivisible by 4 and an address that has nonzero bits in the 4-bit subnet remainder (e.g. 192.168.15.0/22 or f000::/3), the new setting was written to an incorrect location, possibly outside the allocated array.

An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could exploit this to crash chronyd or possibly execute arbitrary code with the privileges of the chronyd process.

CVE-2015-1822 :

Fix initialization of reply slots for authenticated commands.

When allocating memory to save unacknowledged replies to authenticated command requests, the last 'next' pointer was not initialized to NULL. When all allocated reply slots were used, the next reply could be written to an invalid memory instead of allocating a new slot for it.

An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could exploit this to crash chronyd or possibly execute arbitrary code with the privileges of the chronyd process.

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

Miroslav Lichvar of Red Hat discovered multiple vulnerabilities in chrony, an alternative NTP client and server :

  - CVE-2015-1821     Using particular address/subnet pairs when configuring     access control would cause an invalid memory write. This     could allow attackers to cause a denial of service     (crash) or execute arbitrary code.

  - CVE-2015-1822     When allocating memory to save unacknowledged replies to     authenticated command requests, a pointer would be left     uninitialized, which could trigger an invalid memory     write. This could allow attackers to cause a denial of     service (crash) or execute arbitrary code.

  - CVE-2015-1853     When peering with other NTP hosts using authenticated     symmetric association, the internal state variables     would be updated before the MAC of the NTP messages was     validated. This could allow a remote attacker to cause a     denial of service by impeding synchronization between     NTP peers.

Security fix for CVE-2015-1853, CVE-2015-1821, CVE-2015-1822

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

As reported upstream :

When NTP or cmdmon access was configured (from chrony.conf or via authenticated cmdmon) with a subnet size that is indivisible by 4 and an address that has nonzero bits in the 4-bit subnet remainder (e.g.
192.168.15.0/22 or f000::/3), the new setting was written to an incorrect location, possibly outside the allocated array. An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could exploit this to crash chronyd or possibly execute arbitrary code with the privileges of the chronyd process. (CVE-2015-1821)

When allocating memory to save unacknowledged replies to authenticated command requests, the last 'next' pointer was not initialized to NULL.
When all allocated reply slots were used, the next reply could be written to an invalid memory instead of allocating a new slot for it.
An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could exploit this to crash chronyd or possibly execute arbitrary code with the privileges of the chronyd process. (CVE-2015-1822)

An attacker knowing that NTP hosts A and B are peering with each other (symmetric association) can send a packet with random timestamps to host A with source address of B which will set the NTP state variables on A to the values sent by the attacker. Host A will then send on its next poll to B a packet with originate timestamp that doesn't match the transmit timestamp of B and the packet will be dropped. If the attacker does this periodically for both hosts, they won't be able to synchronize to each other. Authentication using a symmetric key can fully protect against this attack, but in implementations following the NTPv3 (RFC 1305) or NTPv4 (RFC 5905) specification the state variables were updated even when the authentication check failed and the association was not protected. (CVE-2015-1853)

The remote Oracle Linux 7 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2015-2241 advisory.

    - update to 2.1 (#1117882 #1169353 #1206504 #1209568 CVE-2015-1821       CVE-2015-1822 CVE-2015-1853)

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.

ID	名稱	產品	系列	已發布	已更新	嚴重性
154559	NewStart CGSL MAIN 6.02 : chrony Multiple Vulnerabilities (NS-SA-2021-0127)	Nessus	NewStart CGSL Local Security Checks	2021/10/27	2025/11/20	high
301211	NewStart CGSL MAIN 6.06 (SP) : chrony Multiple Vulnerabilities (NS-SA-2026-0009)	Nessus	NewStart CGSL Local Security Checks	2026/3/6	2026/3/6	high
82716	Debian DLA-193-1 : chrony security update	Nessus	Debian Local Security Checks	2015/4/13	2021/1/11	medium
82744	Debian DSA-3222-1 : chrony - security update	Nessus	Debian Local Security Checks	2015/4/14	2021/1/11	medium
83067	Fedora 20 : chrony-1.31.1-1.fc20 (2015-5809)	Nessus	Fedora Local Security Checks	2015/4/27	2021/1/11	medium
83978	Amazon Linux AMI : chrony (ALAS-2015-539)	Nessus	Amazon Linux Local Security Checks	2015/6/4	2019/12/18	medium
87032	Oracle Linux 7 : chrony (ELSA-2015-2241)	Nessus	Oracle Linux Local Security Checks	2015/11/24	2024/10/22	medium

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