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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.3712 BIND vulnerability CVE-2021-25219 9 November 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIG-IP and BIG-IQ Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2021-25219 Original Bulletin: https://support.f5.com/csp/article/K77326807 - --------------------------BEGIN INCLUDED TEXT-------------------- K77326807: BIND vulnerability CVE-2021-25219 Original Publication Date: 09 Nov, 2021 Security Advisory Description In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing. (CVE-2021-25219) Impact This vulnerability could be abused by an attacker to significantly degrade resolver performance. Security Advisory Status F5 Product Development has assigned ID 1058153 (BIG-IP) and ID 1058701 (BIG-IQ) to this vulnerability. To determine if your product and version have been evaluated for this vulnerability, refer to the Applies to (see versions) box. To determine if your release is known to be vulnerable, the components or features that are affected by the vulnerability, and for information about releases, point releases, or hotfixes that address the vulnerability, refer to the following table. For more information about security advisory versioning, refer to K51812227: Understanding security advisory versioning. Note: After a fix is introduced for a given minor branch, that fix applies to all subsequent maintenance and point releases for that branch, and no additional fixes for that branch will be listed in the table. For example, when a fix is introduced in 14.1.2.3, the fix also applies to 14.1.2.4, and all later 14.1.x releases (14.1.3.x., 14.1.4.x). For more information, refer to K51812227: Understanding security advisory versioning. Additionally, software versions preceding those listed in the Applies to (see versions) box of this article have reached the End of Technical Support (EoTS) phase of their lifecycle and are no longer evaluated for security issues. For more information, refer to the Security hotfixes section of K4602: Overview of the F5 security vulnerability response policy. +------------+------+--------------+----------+----------+------+-------------+ | | |Versions known|Fixes | |CVSSv3|Vulnerable | |Product |Branch|to be |introduced|Severity |score^|component or | | | |vulnerable^1 |in | |2 |feature | +------------+------+--------------+----------+----------+------+-------------+ | |16.x |16.1.0 - |None | | | | | | |16.1.2 | | | | | | +------+--------------+----------+ | | | | |15.x |15.1.0 - |None | | | | | | |15.1.4 | | | | | | +------+--------------+----------+ | | | | |14.x |14.1.0 - |None | | | | |BIG-IP (all | |14.1.4 | | | | | |modules) +------+--------------+----------+Medium |5.3 |BIND | | |13.x |13.1.0 - |None | | | | | | |13.1.4 | | | | | | +------+--------------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.6 | | | | | | +------+--------------+----------+ | | | | |11.x |11.6.1 - |None | | | | | | |11.6.5 | | | | | +------------+------+--------------+----------+----------+------+-------------+ | |8.x |8.0.0 - 8.1.0 |None | | | | | +------+--------------+----------+ | | | |BIG-IQ |7.x |None |Not | | | | |Centralized | | |applicable|Medium |5.3 |BIND | |Management +------+--------------+----------+ | | | | |6.x |None |Not | | | | | | | |applicable| | | | +------------+------+--------------+----------+----------+------+-------------+ |F5OS |1.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +------------+------+--------------+----------+----------+------+-------------+ |Traffix SDC |5.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +------------+------+--------------+----------+----------+------+-------------+ ^1F5 evaluates only software versions that have not yet reached the End of Technical Support (EoTS) phase of their lifecycle. ^2The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. Recommended Actions If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by installing a version listed in the Fixes introduced in column. If the Fixes introduced in column does not list a version for your branch, then no update candidate currently exists for that branch and F5 recommends upgrading to a version with the fix (refer to the table). If the Fixes introduced in column lists a version prior to the one you are running, in the same branch, then your version should have the fix. Mitigation To mitigate this vulnerability, you can disable the lame cache by setting lame-ttl 0 in the named.conf file. To do so, perform the following procedure. Impact of action: This procedure disables lame caching in the BIND configuration and restarts the system service that may affect the BIG-IP system responding to DNS queries. F5 recommends that you perform this procedure during a scheduled maintenance period. Note: You should perform the procedure for the /var/dnscached/config/named.conf file as well if you are using BIND with the BIG-IP APM module. /var/dnscached/ config/named.conf is valid only if the BIG-IP system is provisioned or was previously provisioned with the BIG-IP APM module. 1. Log in to the Advanced Shell (bash) of the BIG-IP system as the root user. 2. Create a backup of the named.conf file by entering the following command: cp /var/named/config/named.conf /var/named/config/named.conf.SOLK77326807 If you are using BIND with BIG-IP APM, enter the following command: cp /var/dnscached/config/named.conf /var/dnscached/config/ named.conf.SOLK77326807 3. Use an editor of your choice to add the following line to the options stanza of the named.conf file: lame-ttl 0; Repeat this step for the /var/dnscached/config/named.conf as appropriate. 4. If you have modified the configuration of the dnscached service in step 3, you must restart the dnscached service by typing the following command: tmsh restart /sys service dnscached 5. If you have modified the configuration of the named service in step 3, you must restart the named service by typing the following command: tmsh restart /sys service named Supplemental Information o K41942608: Overview of security advisory articles o K4602: Overview of the F5 security vulnerability response policy o K4918: Overview of the F5 critical issue hotfix policy o K8986: F5 software lifecycle policy o K9502: BIG-IP hotfix and point release matrix o K13123: Managing BIG-IP product hotfixes (11.x - 16.x) o K15106: Managing BIG-IQ product hotfixes o K15113: BIG-IQ hotfix and point release matrix o K167: Downloading software and firmware from F5 o K9970: Subscribing to email notifications regarding F5 products o K9957: Creating a custom RSS feed to view new and updated documents - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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