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             AUSCERT External Security Bulletin Redistribution

           K11742742: iControl REST vulnerability CVE-2022-23023
                               23 April 2022


        AusCERT Security Bulletin Summary

Product:           BIG-IP
Publisher:         F5 Networks
Operating System:  Network Appliance
Resolution:        Patch/Upgrade
CVE Names:         CVE-2022-23023  

Original Bulletin: 

Comment: CVSS (Max):  6.5 CVE-2022-23023 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
         CVSS Source: F5
         Calculator:  https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Revision History:  April   23 2022: Vendor added fixed version for BIG-IP
                   January 21 2022: Initial Release

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K11742742: iControl REST vulnerability CVE-2022-23023

Original Publication Date: 19 Jan, 2022
Latest   Publication Date: 19 Apr, 2022

Security Advisory Description

Undisclosed requests by an authenticated iControl REST user can cause an
increase in memory resource utilization. (CVE-2022-23023)


System performance can degrade until the process is either forced to restart or
is manually restarted. This vulnerability allows an authenticated remote
attacker to cause a degradation of service that can lead to a
denial-of-service (DoS) on the BIG-IP system.

Security Advisory Status

F5 Product Development has assigned ID 940185 (BIG-IP and BIG-IQ) to this
vulnerability. This issue has been classified as CWE-400: Uncontrolled Resource

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, the fix also applies to, 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 -      |  |          |      |             |
|            |      |16.1.2        |          |          |      |             |
|            +------+--------------+----------+          |      |             |
|            |15.x  |15.1.0 -      |15.1.5    |          |      |             |
|            |      |15.1.4        |          |          |      |             |
|            +------+--------------+----------+          |      |             |
|            |14.x  |14.1.0 -      |  |          |      |             |
|BIG-IP (all |      |14.1.4        |          |          |      |             |
|modules)    +------+--------------+----------+Medium    |6.5   |iControl REST|
|            |13.x  |13.1.0 -      |13.1.5    |          |      |             |
|            |      |13.1.4        |          |          |      |             |
|            +------+--------------+----------+          |      |             |
|            |12.x  |12.1.0 -      |Will not  |          |      |             |
|            |      |12.1.5        |fix       |          |      |             |
|            +------+--------------+----------+          |      |             |
|            |11.x  |None          |Not       |          |      |             |
|            |      |              |applicable|          |      |             |
|BIG-IQ      |8.x   |8.0.0 - 8.1.0 |None      |          |      |             |
|Centralized +------+--------------+----------+Medium    |6.5   |iControl REST|
|Management  |7.x   |7.0.0 - 7.1.0 |None      |          |      |             |
|F5OS-A      |1.x   |None          |Not       |Not       |None  |None         |
|            |      |              |applicable|vulnerable|      |             |
|F5OS-C      |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 upgrading to a version listed
in the Fixes introduced in column. If the table lists only an older version
than what you are currently running, or does not list a non-vulnerable version,
then no upgrade candidate currently exists.


As this attack is conducted by legitimate, authenticated users, there is no
viable mitigation that also allows users access to the Configuration utility.
The only mitigation is to remove access for users who are not completely

Until it is possible to install a fixed version, you can use the following
sections as temporary mitigations. These mitigations restrict access to
iControl REST to only trusted networks or devices, thereby limiting the attack

  o Block iControl REST access through the self IP address
  o Block iControl REST access through the management interface

Block iControl REST access through the self IP address

You can block all access to the iControl REST interface of your BIG-IP
or BIG-IQ system through self IP addresses. To do so, you can change the Port
Lockdown setting to Allow None for each self IP address in the system. If you
must open any ports, you should use the Allow Custom option, taking care to
disallow access to iControl REST. By default, iControl REST listens on TCP port
443 or TCP port 8443 on single NIC BIG-IP VE instances. If you modified the
default port, ensure that you disallow access to the alternate port you

Note: Performing this action prevents all access to the Configuration utility
and iControl REST using the self IP address. These changes may also impact
other services, including breaking high availability (HA) configurations.

Before you make changes to the configuration of your self IP addresses, F5
strongly recommends that you refer to the following articles:

  o K17333: Overview of port lockdown behavior (12.x - 16.x)
  o K39403510: Managing the port lockdown configuration on the BIG-IQ system
  o K13092: Overview of securing access to the BIG-IP system
  o K31003634: The Configuration utility of the Single-NIC BIG-IP Virtual
    Edition now defaults to TCP port 8443
  o K51358480: The single-NIC BIG-IP VE may erroneously revert to the default
    management httpd port after a configuration reload

If you must expose port 443 on your self IP addresses and want to restrict
access to specific IP ranges, you may consider using the packet filtering
functionality built into the BIG-IP system. For more information, refer to the
following article:

  o K13383: Configuring CIDR Network Addresses for the BIG-IP packet filter

For BIG-IQ self IP addresses where port 443 is exposed, use an external packet
filtering device such as BIG-IP AFM.

Block iControl REST access through the management interface

To mitigate this vulnerability for affected F5 products, you should restrict
management access to only trusted users and devices over a secure network. For
more information about securing access to BIG-IP or BIG-IQ systems, refer to
the following articles:

  o K13092: Overview of securing access to the BIG-IP system
  o K46122561: Restricting access to the management interface using network
    firewall rules 
  o K92748202: Restricting access to the BIG-IQ management interface using
    network firewall rules
  o K69354049: Restricting access to the BIG-IP management interface for
    Configuration utility and iControl REST services using iptables

Note: For BIG-IQ 7.x, secure the management interface by using an external
packet filtering device such as BIG-IP AFM.


This issue was discovered internally by F5.

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

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