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AUSCERT External Security Bulletin Redistribution
ESB-2021.0980
TMM vulnerability CVE-2021-23007
22 March 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: BIG-IP Products
Publisher: F5 Networks
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-23007
Original Bulletin:
https://support.f5.com/csp/article/K37451543
- --------------------------BEGIN INCLUDED TEXT--------------------
K37451543: TMM vulnerability CVE-2021-23007
Original Publication Date: 20 Mar, 2021
Security Advisory Description
When the Traffic Management Microkernel (TMM) process handles certain
undisclosed traffic, it may start dropping all fragmented IP traffic.
(CVE-2021-23007)
Impact
TMM incorrectly determines that the fragment memory limit has been reached and
drops all fragments it receives, disrupting traffic to the BIG-IP system.
You can determine if your system is impacted by running the tmctl ip_stat
command from the BIG-IP command line and reviewing the output for an unusually
large value in the frag_bytes_used column for a given TMM. You may observe that
some TMM processes have high values and others do not. For example:
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
46406517 508 0 0
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
44739031 217 0 0
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
39322744 8404728 8404628 18446744073709547072
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
33528060 15659496 15659334 18446744073709547072
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
46712180 157 0 0
rx_frag rx_frag_dropped err_frag_mem_limit_reached frag_bytes_used
-------- --------------- -------------------------- --------------------
38912369 10588696 10588558 18446744073709547072
Security Advisory Status
F5 Product Development has assigned ID 1002561 (BIG-IP) 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 vulnerable version, that fix applies to
all subsequent point releases for that version and no additional fixes for that
version will be listed in the table. For example, when a fix is introduced in
14.1.2.3, the fix applies to 14.1.2.4 and all later point releases.
+-----------+------+----------+-------------------------------------+----------+------+----------+
| | |Versions | | |CVSSv3|Vulnerable|
|Product |Branch|known to |Fixes introduced in |Severity |score^|component |
| | |be | | |1 |or feature|
| | |vulnerable| | | | |
+-----------+------+----------+-------------------------------------+----------+------+----------+
| |16.x |16.0.1.1 |Hotfix-BIGIP-16.0.1.1.9.6-ENG.iso^2 | | | |
| +------+----------+-------------------------------------+ | | |
| |15.x |None |Not applicable | | | |
| +------+----------+-------------------------------------+ | | |
| |14.x |14.1.4 |Hotfix-BIGIP-14.1.4.0.120.11-ENG.iso^| | |TMM (IP |
|BIG-IP (all| | |2 |Medium |5.3 |Fragment |
|modules) +------+----------+-------------------------------------+ | |Handling) |
| |13.x |None |Not applicable | | | |
| +------+----------+-------------------------------------+ | | |
| |12.x |None |Not applicable | | | |
| +------+----------+-------------------------------------+ | | |
| |11.x |None |Not applicable | | | |
+-----------+------+----------+-------------------------------------+----------+------+----------+
| |8.x |None |Not applicable | | | |
|BIG-IQ +------+----------+-------------------------------------+Not | | |
|Centralized|7.x |None |Not applicable |vulnerable|None |None |
|Management +------+----------+-------------------------------------+ | | |
| |6.x |None |Not applicable | | | |
+-----------+------+----------+-------------------------------------+----------+------+----------+
|F5OS |1.x |None |Not applicable |Not |None |None |
| | | | |vulnerable| | |
+-----------+------+----------+-------------------------------------+----------+------+----------+
|Traffix SDC|5.x |None |Not applicable |Not |None |None |
| | | | |vulnerable| | |
+-----------+------+----------+-------------------------------------+----------+------+----------+
^1The CVSSv3 score link takes you to a resource outside of AskF5, and it is
possible that the document may be removed without our knowledge.
^2You can download engineering hotfix releases from the following locations:
o Engineering hotfix for 16.0.1.1: https://downloads.f5.com/esd/ecc.svsw=
BIG-IP&pro=big-ip_v16.x&ver=16.0.1&container=HotFix-BIGIP-16.0.1.1.9.6-EHF9
o Engineering hotfix for 14.1.4: https://downloads.f5.com/esd/ecc.svsw=
BIG-IP&pro=big-ip_v14.x&ver=14.1.4&container=
HotFix-BIGIP-14.1.4.0.120.11-EHF120
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
You can restart the TMM process to recover from the condition; however, this is
not a permanent fix. To do so, perform the following procedure:
Impact of procedure: Performing the following procedure causes a temporary
traffic disruption while the TMM process restarts. You should perform this
procedure only during a scheduled maintenance period.
1. Log in to the TMOS Shell (tmsh) by entering the following command:
tmsh
2. To restart the TMM process, enter the following command:
restart /sys service tmm
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 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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