Synopsis: Low: unbound security and bug fix update
Advisory ID: SLSA-2015:2455-1
Issue Date: 2015-11-19
CVE Numbers: CVE-2014-8602
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.
– Scientific Linux Development Team