Scientific Linux Security Update : unbound on SL7.x x86_64
Medium Nessus Plugin ID 87577
SynopsisThe remote Scientific Linux host is missing one or more security updates.
DescriptionA 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.
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.
SolutionUpdate the affected packages.