The Cisco Application Control Engine (ACE) software installed on the remote Cisco ACE 4710 device or ACE30 module is version A5 prior to A5(3.3). It is, therefore, affected by multiple vulnerabilities :

  - An invalid free memory error exists due to improper     validation of user-supplied input when a DTLS peer     receives application data between ChangeCipherSpec and     Finished messages. A remote attacker can exploit this to     corrupt memory, resulting in a denial of service or     the execution of arbitrary code. (CVE-2014-8176)

  - A denial of service vulnerability exists when processing     an ECParameters structure due to an infinite loop that     occurs when a specified curve is over a malformed binary     polynomial field. A remote attacker can exploit this to     perform a denial of service against any system that     processes public keys, certificate requests, or     certificates. This includes TLS clients and TLS servers     with client authentication enabled. (CVE-2015-1788)

  - A denial of service vulnerability exists due to improper     validation of the content and length of the ASN1_TIME     string by the X509_cmp_time() function. A remote     attacker can exploit this, via a malformed certificate     and CRLs of various sizes, to cause a segmentation     fault, resulting in a denial of service condition. TLS     clients that verify CRLs are affected. TLS clients and     servers with client authentication enabled may be     affected if they use custom verification callbacks.
    (CVE-2015-1789)

  - A NULL pointer dereference flaw exists in the PKCS#7     parsing code due to incorrect handling of missing inner     'EncryptedContent'. This allows a remote attacker, via     specially crafted ASN.1-encoded PKCS#7 blobs with     missing content, to cause a denial of service condition     or other potential unspecified impacts. (CVE-2015-1790)

  - A double-free error exists due to a race condition that     occurs when a NewSessionTicket is received by a     multi-threaded client when attempting to reuse a     previous ticket. A remote attacker can exploit this to     cause a denial of service condition or other potential     unspecified impact. (CVE-2015-1791)

  - A denial of service vulnerability exists in the CMS code     due to an infinite loop that occurs when verifying a     signedData message. A remote attacker can exploit this     to cause a denial of service condition. (CVE-2015-1792)

  - The symmetric-key feature in the receive function     requires a correct message authentication code (MAC)     only if the MAC field has a nonzero length. This makes     it easier for a man-in-the-middle attacker to spoof     packets by omitting the MAC. (CVE-2015-1798)

  - A flaw exists in the symmetric-key feature in the     receive function when handling a specially crafted     packet sent to one of two hosts that are peering with     each other. This allows an attacker to cause the next     attempt by the servers to synchronize to fail.
    (CVE-2015-1799)

  - A man-in-the-middle vulnerability, known as Logjam,     exists due to a flaw in the SSL/TLS protocol. A remote     attacker can exploit this flaw to downgrade connections     using ephemeral Diffie-Hellman key exchange to 512-bit     export-grade cryptography. (CVE-2015-4000)

  - A flaw exists in the TLS 1.x implementation in the     Cavium SDK due to a failure to check the first byte of     the padding bytes. A man-in-the-middle attacker can     exploit this, by sending specially crafted requests to     the server, to induce requests that allow determining     the plaintext chunks of data. This vulnerability is a     variant of the POODLE attack. (CVE-2015-4595)

Brief introduction 

CVE-2015-1798

When ntpd is configured to use a symmetric key to authenticate a remote NTP server/peer, it checks if the NTP message authentication code (MAC) in received packets is valid, but not if there actually is any MAC included. Packets without a MAC are accepted as if they had a valid MAC. This allows a MITM attacker to send false packets that are accepted by the client/peer without having to know the symmetric key.
The attacker needs to know the transmit timestamp of the client to match it in the forged reply and the false reply needs to reach the client before the genuine reply from the server. The attacker doesn't necessarily need to be relaying the packets between the client and the server. Authentication using autokey doesn't have this problem as there is a check that requires the key ID to be larger than NTP_MAXKEY, which fails for packets without a MAC.

CVE-2015-1799

An attacker knowing that NTP hosts A and B are peering with each other (symmetric association) can send a packet 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. This is a known denial of service attack, described at https://www.eecis.udel.edu/~mills/onwire.html . According to the document the NTP authentication is supposed to protect symmetric associations against this attack, but that doesn't seem to be the case. The state variables are updated even when authentication fails and the peers are sending packets with originate timestamps that don't match the transmit timestamps on the receiving side.

ntp-keygen on big endian hosts

Using ntp-keygen to generate an MD5 key on big endian hosts resulted in either an infite loop or an key of only 93 possible keys.

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-2015-1799, CVE-2015-1798, #1210324

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 symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 4.x before 4.2.8p2 requires a correct MAC only if the MAC field has a nonzero length, which makes it easier for man-in-the-middle attackers to spoof packets by omitting the MAC.
(CVE-2015-1798)

The symmetric-key feature in the receive function in ntp_proto.c in ntpd in NTP 3.x and 4.x before 4.2.8p2 performs state-variable updates upon receiving certain invalid packets, which makes it easier for man-in-the-middle attackers to cause a denial of service (synchronization loss) by spoofing the source IP address of a peer.
(CVE-2015-1799)

This update also addresses leap-second handling. With older ntp versions, the -x option was sometimes used as a workaround to avoid kernel inserting/deleting leap seconds by stepping the clock and possibly upsetting running applications. That no longer works with 4.2.6 as ntpd steps the clock itself when a leap second occurs. The fix is to treat the one second offset gained during leap second as a normal offset and check the stepping threshold (set by -x or tinker step) to decide if a step should be applied. See this forum post for more information on the Amazon Linux AMI's leap-second handling.

ntp.org reports :

- [Sec 2779] ntpd accepts unauthenticated packets with symmetric key crypto.

- [Sec 2781] Authentication doesn't protect symmetric associations against DoS attacks.

Multiple vulnerabilities were discovered in ntp, an implementation of the Network Time Protocol :

  - CVE-2015-1798     When configured to use a symmetric key with an NTP peer,     ntpd would accept packets without MAC as if they had a     valid MAC. This could allow a remote attacker to bypass     the packet authentication and send malicious packets     without having to know the symmetric key.

  - CVE-2015-1799     When peering with other NTP hosts using authenticated     symmetric association, ntpd would update its internal     state variables 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.

Additionally, it was discovered that generating MD5 keys using ntp-keygen on big endian machines would either trigger an endless loop, or generate non-random keys.

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.

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.

Network Time Protocol (NTP) Project NTP daemon (ntpd) is vulnerable to a denial of service, caused by an error when using symmetric key authentication. By sending specially-crafted packets to both peering hosts, an attacker could exploit this vulnerability to prevent synchronization.

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-9297 Network Time Protocol (NTP) Project NTP daemon (ntpd) could allow a remote attacker to conduct spoofing attacks, caused by insufficient entropy in PRNG. An attacker could exploit this vulnerability to spoof the IPv6 address ::1 to bypass ACLs and launch further attacks on the system. Network Time Protocol (NTP) Project NTP daemon (ntpd) is vulnerable to a denial of service, caused by an error when using symmetric key authentication. By sending specially-crafted packets to both peering hosts, an attacker could exploit this vulnerability to prevent synchronization.

The remote host is affected by the vulnerability described in GLSA-201509-01 (NTP: Multiple vulnerablities)

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

    A remote attacker could possibly execute arbitrary code with the       privileges of the process, or cause a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

ID	名前	製品	ファミリー	公開日	更新日	深刻度
91427	Cisco ACE 4710 Appliance / ACE30 Module Multiple Vulnerabilities (Logjam)	Nessus	CISCO	2016/6/1	2022/12/5	high
82715	Debian DLA-192-1 : ntp security update	Nessus	Debian Local Security Checks	2015/4/13	2021/1/11	medium
83010	Fedora 20 : ntp-4.2.6p5-22.fc20 (2015-5874)	Nessus	Fedora Local Security Checks	2015/4/23	2021/1/11	medium
83271	Amazon Linux AMI : ntp (ALAS-2015-520)	Nessus	Amazon Linux Local Security Checks	2015/5/7	2018/4/18	medium
82631	FreeBSD : ntp -- multiple vulnerabilities (ebd84c96-dd7e-11e4-854e-3c970e169bc2)	Nessus	FreeBSD Local Security Checks	2015/4/8	2021/1/6	medium
82745	Debian DSA-3223-1 : ntp - security update	Nessus	Debian Local Security Checks	2015/4/14	2021/1/11	high
83008	Fedora 22 : ntp-4.2.6p5-30.fc22 (2015-5761)	Nessus	Fedora Local Security Checks	2015/4/23	2021/1/11	medium
87030	Oracle Linux 7 : ntp (ELSA-2015-2231)	Nessus	Oracle Linux Local Security Checks	2015/11/24	2025/8/29	high
87143	CentOS 7 : ntp (CESA-2015:2231)	Nessus	CentOS Local Security Checks	2015/12/2	2021/1/4	high
85603	AIX 6.1 TL 9 : ntp (IV73783)	Nessus	AIX Local Security Checks	2015/8/25	2023/4/21	medium
85605	AIX 7.1 TL 2 : ntp (IV74262)	Nessus	AIX Local Security Checks	2015/8/25	2023/4/21	medium
84492	AIX 6.1 TL 6 : ntp4 (IV71094)	Nessus	AIX Local Security Checks	2015/7/2	2023/4/21	medium
86132	GLSA-201509-01 : NTP: Multiple vulnerablities	Nessus	Gentoo Local Security Checks	2015/9/25	2021/1/11	medium

検出

プラグインの検索

high

medium

medium

medium

medium

high

medium

high

high

medium

medium

medium

medium