The remote Oracle Linux 7 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2015-2455 advisory.

    - Fix CVE-2014-8602 (#1253961)

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

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

Florian Maury from ANSSI discovered that unbound, a validating, recursive, and caching DNS resolver, was prone to a denial of service vulnerability. An attacker crafting a malicious zone and able to emit (or make emit) queries to the server can trick the resolver into following an endless series of delegations, leading to resource exhaustion and huge network usage.

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.

Updated unbound packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

A denial of service flaw was found in unbound that an attacker could use to trick the unbound resolver into following an endless loop of delegations, consuming an excessive amount of resources.
(CVE-2014-8602)

This update also fixes the following bugs :

* Prior to this update, there was a mistake in the time configuration in the cron job invoking unbound-anchor to update the root zone key.
Consequently, unbound-anchor was invoked once a month instead of every day, thus not complying with RFC 5011. The cron job has been replaced with a systemd timer unit that is invoked on a daily basis. Now, the root zone key validity is checked daily at a random time within a 24-hour window, and compliance with RFC 5011 is ensured. (BZ#1180267)

* Previously, the unbound packages were installing their configuration file for the systemd-tmpfiles utility into the /etc/tmpfiles.d/ directory. As a consequence, changes to unbound made by the administrator in /etc/tmpfiles.d/ could be overwritten on package reinstallation or update. To fix this bug, unbound has been amended to install the configuration file into the /usr/lib/tmpfiles.d/ directory. As a result, the system administrator's configuration in /etc/tmpfiles.d/ is preserved, including any changes, on package reinstallation or update. (BZ#1180995)

* The unbound server default configuration included validation of DNS records using the DNSSEC Look-aside Validation (DLV) registry. The Internet Systems Consortium (ISC) plans to deprecate the DLV registry service as no longer needed, and unbound could execute unnecessary steps. Therefore, the use of the DLV registry has been removed from the unbound server default configuration. Now, unbound does not try to perform DNS records validation using the DLV registry. (BZ#1223339)

All unbound users are advised to upgrade to these updated packages, which contain backported patches to correct these issues.

A denial of service flaw was found in unbound that an attacker could use to trick the unbound resolver into following an endless loop of delegations, consuming an excessive amount of resources.
(CVE-2014-8602)

This update also fixes the following bugs :

  - Prior to this update, there was a mistake in the time     configuration in the cron job invoking unbound-anchor to     update the root zone key. Consequently, unbound-anchor     was invoked once a month instead of every day, thus not     complying with RFC 5011. The cron job has been replaced     with a systemd timer unit that is invoked on a daily     basis. Now, the root zone key validity is checked daily     at a random time within a 24-hour window, and compliance     with RFC 5011 is ensured.

  - Previously, the unbound packages were installing their     configuration file for the systemd-tmpfiles utility into     the /etc/tmpfiles.d/ directory. As a consequence,     changes to unbound made by the administrator in     /etc/tmpfiles.d/ could be overwritten on package     reinstallation or update. To fix this bug, unbound has     been amended to install the configuration file into the     /usr/lib/tmpfiles.d/ directory. As a result, the system     administrator's configuration in /etc/tmpfiles.d/ is     preserved, including any changes, on package     reinstallation or update.

  - The unbound server default configuration included     validation of DNS records using the DNSSEC Look-aside     Validation (DLV) registry. The Internet Systems     Consortium (ISC) plans to deprecate the DLV registry     service as no longer needed, and unbound could execute     unnecessary steps. Therefore, the use of the DLV     registry has been removed from the unbound server     default configuration. Now, unbound does not try to     perform DNS records validation using the DLV registry.

The remote MiracleLinux 7 host has packages installed that are affected by a vulnerability as referenced in the AXSA:2015-838:01 advisory.

    Unbound is a validating, recursive, and caching DNS(SEC) resolver.
    The C implementation of Unbound is developed and maintained by NLnet     Labs. It is based on ideas and algorithms taken from a java prototype     developed by Verisign labs, Nominet, Kirei and ep.net.
    Unbound is designed as a set of modular components, so that also     DNSSEC (secure DNS) validation and stub-resolvers (that do not run     as a server, but are linked into an application) are easily possible.
    Security issues fixed with this release:
    CVE-2014-8602     iterator.c in NLnet Labs Unbound before 1.5.1 does not limit     delegation chaining, which allows remote attackers to cause a denial     of service (memory and CPU consumption) via a large or infinite number     of referrals.
    Fixed bugs:
    * Prior to this update, there was a mistake in the time configuration in the cron job invoking unbound-     anchor to update the root zone key. Consequently, unbound-anchor was invoked once a month instead of every     day, thus not complying with RFC 5011. The cron job has been replaced with a systemd timer unit that is     invoked on a daily basis. Now, the root zone key validity is checked daily at a random time within a     24-hour window, and compliance with RFC 5011 is ensured.
    * Previously, the unbound packages were installing their configuration file for the systemd-tmpfiles     utility into the /etc/tmpfiles.d/ directory. As a consequence, changes to unbound made by the     administrator in /etc/tmpfiles.d/ could be overwritten on package reinstallation or update. To fix this     bug, unbound has been amended to install the configuration file into the /usr/lib/tmpfiles.d/ directory.
    As a result, the system administrator's configuration in /etc/tmpfiles.d/ is preserved, including any     changes, on package reinstallation or update.
    * The unbound server default configuration included validation of DNS records using the DNSSEC Look-aside     Validation (DLV) registry. The Internet Systems Consortium (ISC) plans to deprecate the DLV registry     service as no longer needed, and unbound could execute unnecessary steps. Therefore, the use of the DLV     registry has been removed from the unbound server default configuration. Now, unbound does not try to     perform DNS records validation using the DLV registry.

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

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

Unbound developer reports :

The resolver can be tricked into following an endless series of delegations, this consumes a lot of resources.

ID	名称	产品	系列	发布时间	最近更新时间	严重程度
87041	Oracle Linux 7 : unbound (ELSA-2015-2455)	Nessus	Oracle Linux Local Security Checks	2015/11/24	2024/11/1	high
82091	Debian DLA-107-1 : unbound security update	Nessus	Debian Local Security Checks	2015/3/26	2021/1/11	medium
86991	RHEL 7 : unbound (RHSA-2015:2455)	Nessus	Red Hat Local Security Checks	2015/11/20	2019/10/24	medium
87577	Scientific Linux Security Update : unbound on SL7.x x86_64 (20151119)	Nessus	Scientific Linux Local Security Checks	2015/12/22	2021/1/14	medium
289261	MiracleLinux 7 : unbound-1.4.20-26.el7 (AXSA:2015-838:01)	Nessus	Miracle Linux Local Security Checks	2026/1/16	2026/1/16	high
79810	FreeBSD : unbound -- can be tricked into following an endless series of delegations, this consumes a lot of resources (10d73529-7f4b-11e4-af66-00215af774f0)	Nessus	FreeBSD Local Security Checks	2014/12/9	2021/1/6	medium

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