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.

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.

The remote host is affected by the vulnerability described in GLSA-201507-01 (chrony: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in chrony. Please review       the CVE identifiers referenced below for details.
  Impact :

    A remote attacker can cause arbitrary remote code execution or Denial of       service condition.
  Workaround :

    There is no known workaround at this time.

Chrony News reports :

CVE-2015-1853: DoS attack on authenticated symmetric NTP associations

CVE-2015-1821: Heap-based buffer overflow in access configuration

CVE-2015-1822: Use of uninitialized pointer in command processing

An out-of-bounds write flaw was found in the way chrony stored certain addresses when configuring NTP or cmdmon access. An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could use this flaw to crash chronyd or, possibly, execute arbitrary code with the privileges of the chronyd process.
(CVE-2015-1821)

An uninitialized pointer use flaw was found when allocating memory to save unacknowledged replies to authenticated command requests. An attacker that has the command key and is allowed to access cmdmon (only localhost is allowed by default) could use this flaw to crash chronyd or, possibly, execute arbitrary code with the privileges of the chronyd process. (CVE-2015-1822)

A denial of service flaw was found in the way chrony 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-2015-1853)

The chrony packages have been upgraded to upstream version 2.1.1, which provides a number of bug fixes and enhancements over the previous version. Notable enhancements include :

  - Updated to NTP version 4 (RFC 5905)

  - Added pool directive to specify pool of NTP servers

  - Added leapsecmode directive to select how to correct     clock for leap second

  - Added smoothtime directive to smooth served time and     enable leap smear

  - Added asynchronous name resolving with POSIX threads

  - Ready for year 2036 (next NTP era)

  - Improved clock control

  - Networking code reworked to open separate client sockets     for each NTP server

This update also fixes the following bug :

  - The chronyd service previously assumed that network     interfaces specified with the 'bindaddress' directive     were ready when the service was started. This could     cause chronyd to fail to bind an NTP server socket to     the interface if the interface was not ready. With this     update, chronyd uses the IP_FREEBIND socket option,     enabling it to bind to an interface later, not only when     the service starts.

In addition, this update adds the following enhancement :

  - The chronyd service now supports four modes of handling     leap seconds, configured using the 'leapsecmode' option.
    The clock can be either stepped by the kernel (the     default 'system' mode), stepped by chronyd ('step'     mode), slowly adjusted by slewing ('slew' mode), or the     leap second can be ignored and corrected later in normal     operation ('ignore' mode). If you select slewing, the     correction will always start at 00:00:00 UTC and will be     applied at a rate specified in the 'maxslewrate' option.

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
83009	Fedora 21 : chrony-1.31.1-1.fc21 (2015-5816)	Nessus	Fedora Local Security Checks	2015/4/23	2021/1/11	medium
84531	GLSA-201507-01 : chrony: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	2015/7/6	2021/1/11	medium
82892	FreeBSD : chrony -- multiple vulnerabilities (c4571ca8-053d-44c9-ab3c-89b1372ad0a5)	Nessus	FreeBSD Local Security Checks	2015/4/20	2021/1/6	medium
87551	Scientific Linux Security Update : chrony on SL7.x x86_64 (20151119)	Nessus	Scientific Linux Local Security Checks	2015/12/22	2021/1/14	medium

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