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AUSCERT External Security Bulletin Redistribution
ESB-2022.0296
K41415626: Transparent DNS Cache can consume excessive resources
21 January 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: BIG-IP DNS
BIG-IP GTM
BIG-IP LTM
Publisher: F5 Networks
Operating System: Network Appliance
Impact/Access: Reduced Security -- Unknown/Unspecified
Resolution: Patch/Upgrade
Original Bulletin:
https://support.f5.com/csp/article/K41415626
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K41415626: Transparent DNS Cache can consume excessive resources
Original Publication Date: 19 Jan, 2022
Security Advisory Description
When transparent Domain Name System (DNS) cache is configured on a virtual
server, undisclosed Extension Mechanisms for DNS (EDNS0) queries can cause the
BIG-IP system to send a large volume of User Datagram Protocol (UDP) traffic on
the server side.
This issue occurs when all of the following conditions are met:
o Transparent DNS Cache is enabled.
o EDNS is enabled.
Impact
This can cause the BIG-IP system to send a large volume of UDP traffic to the
server side.
Symptoms
As a result of this issue, you may encounter the following symptom:
o Increase in BIG-IP server-side UDP traffic.
Security Advisory Status
F5 Product Development has assigned ID 1035853 to this issue. This issue has
been classified as CWE-20: Improper Input Validation.
To determine if your product and version have been evaluated for this issue,
refer to the Applies to (see versions) box. To determine if your release is
affected by this issue and for information about releases, point releases, or
hotfixes that address the issue, 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.
+------------------------+------+----------------------------+----------------+
|Product |Branch|Versions affected by this |Fixes introduced|
| | |issue^1 |in |
+------------------------+------+----------------------------+----------------+
| |16.x |16.1.0 - 16.1.1 |16.1.2 |
| +------+----------------------------+----------------+
| |15.x |15.1.0 - 15.1.4 |15.1.5 |
| +------+----------------------------+----------------+
| |14.x |14.1.0 - 14.1.4 |14.1.4.5 |
|BIG-IP (DNS, GTM, LTM) +------+----------------------------+----------------+
| |13.x |13.1.0 - 13.1.4 |None |
| +------+----------------------------+----------------+
| |12.x |12.1.0 - 12.1.6 |Will not fix |
| +------+----------------------------+----------------+
| |11.x |11.6.1 - 11.6.5 |Will not fix |
+------------------------+------+----------------------------+----------------+
| |16.x |None |Not applicable |
| +------+----------------------------+----------------+
| |15.x |None |Not applicable |
| +------+----------------------------+----------------+
|BIG-IP (all other |14.x |None |Not applicable |
|modules) +------+----------------------------+----------------+
| |13.x |None |Not applicable |
| +------+----------------------------+----------------+
| |12.x |None |Not applicable |
| +------+----------------------------+----------------+
| |11.x |None |Not applicable |
+------------------------+------+----------------------------+----------------+
|BIG-IQ Centralized |8.x |None |Not applicable |
|Management +------+----------------------------+----------------+
| |7.x |None |Not applicable |
+------------------------+------+----------------------------+----------------+
|F5OS-A |1.x |None |Not applicable |
+------------------------+------+----------------------------+----------------+
|F5OS-C |1.x |None |Not applicable |
+------------------------+------+----------------------------+----------------+
| |3.x |None |Not applicable |
| +------+----------------------------+----------------+
|NGINX App Protect |2.x |None |Not applicable |
| +------+----------------------------+----------------+
| |1.x |None |Not applicable |
+------------------------+------+----------------------------+----------------+
^1F5 evaluates only software versions that have not yet reached the End of
Technical Support (EoTS) phase of their lifecycle.
Recommended Actions
If you are running a version listed in the Versions affected by this issue
column, you can eliminate this issue 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
None
Acknowledgements
This issue was discovered internally by F5.
Supplemental Information
o K51812227: Understanding security advisory versioning
o K41942608: Overview of AskF5 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 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
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