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AUSCERT External Security Bulletin Redistribution
ESB-2019.4453
BIG-IP Engineering Hotfix authentication bypass vulnerability CVE-2019-6675
26 November 2019
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: F5 BIG-IP products
Publisher: F5 Networks
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2019-6675
Original Bulletin:
https://support.f5.com/csp/article/K55655944
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K55655944: BIG-IP Engineering Hotfix authentication bypass vulnerability CVE-2019-6675
Security Advisory
Original Publication Date: 26 Nov, 2019
Security Advisory Description
BIG-IP configurations using Active Directory, LDAP, or Client Certificate LDAP
for management authentication with multiple servers are exposed to a
vulnerability which allows an authentication bypass. This can result in a
complete compromise of the system. This issue only impacts specific engineering
hotfixes using the aforementioned authentication configuration. (CVE-2019-6675)
Impact
Remote users authenticating to the BIG-IP system using LDAP, Active Directory,
or Client Certificate LDAP are able to log in with incorrect credentials
resulting in a complete compromise of the BIG-IP system.
Important: This vulnerability impacts only BIG-IP Engineering Hotfixes you
obtained from F5 Support. Refer to the table in the following section for the
list of affected versions. To verify if you are running an affected version
from this list, perform the procedure in the Recommended Actions section. This
vulnerability does not affect any of the BIG-IP major, minor, or maintenance
releases you obtained from downloads.f5.com.
Security Advisory Status
F5 Product Development has assigned ID 849761 (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.
+-----------+------+-------------------------+-----------+----------+------+--------------+
| | |Versions known to be |Fixes | |CVSSv3|Vulnerable |
|Product |Branch|vulnerable |introduced |Severity |score^|component or |
| | | |in | |1 |feature |
+-----------+------+-------------------------+-----------+----------+------+--------------+
| | |15.0.1.0.33.11-ENG Hotfix|Not | | | |
| |15.x |15.0.1.0.48.11-ENG Hotfix|applicable^| | | |
| | | |2 | | | |
| +------+-------------------------+-----------+ | | |
| | |14.1.0.3.0.79.6-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.3.0.97.6-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.3.0.99.6-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.5.0.15.5-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.5.0.36.5-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.5.0.40.5-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.6.0.11.9-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.6.0.14.9-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.6.0.68.9-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.0.6.0.70.9-ENG | | | | |
|BIG-IP | |Hotfix | | | | |
|(LTM, AAM, | |14.1.2.0.11.37-ENG Hotfix|Not | | | |
|AFM, |14.x |14.1.2.0.18.37-ENG Hotfix|applicable^| | | |
|Analytics, | |14.1.2.0.32.37-ENG Hotfix|2 | | |BIG-IP |
|APM, ASM, | |14.1.2.1.0.46.4-ENG | |Critical |9.8 |administrative|
|DNS, FPS, | |Hotfix | | | |authentication|
|GTM, Link | |14.1.2.1.0.14.4-ENG | | | | |
|Controller,| |Hotfix | | | | |
|PEM) | |14.1.2.1.0.16.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.34.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.97.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.99.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.105.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.111.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.115.4-ENG | | | | |
| | |Hotfix | | | | |
| | |14.1.2.1.0.122.4-ENG | | | | |
| | |Hotfix | | | | |
| +------+-------------------------+-----------+ | | |
| |13.x |None |Not | | | |
| | | |applicable | | | |
| +------+-------------------------+-----------+ | | |
| |12.x |None |Not | | | |
| | | |applicable | | | |
| +------+-------------------------+-----------+ | | |
| |11.x |None |Not | | | |
| | | |applicable | | | |
+-----------+------+-------------------------+-----------+----------+------+--------------+
|Enterprise |3.x |None |Not |Not |None |None |
|Manager | | |applicable |vulnerable| | |
+-----------+------+-------------------------+-----------+----------+------+--------------+
| |7.x |None |Not | | | |
| | | |applicable | | | |
|BIG-IQ +------+-------------------------+-----------+ | | |
|Centralized|6.x |None |Not |Not |None |None |
|Management | | |applicable |vulnerable| | |
| +------+-------------------------+-----------+ | | |
| |5.x |None |Not | | | |
| | | |applicable | | | |
+-----------+------+-------------------------+-----------+----------+------+--------------+
|F5 |2.x |None |Not |Not |one |None |
|iWorkflow | | |applicable |vulnerable| | |
+-----------+------+-------------------------+-----------+----------+------+--------------+
|Traffix SDC|5.x |None |Not |Not |None |None |
| | | |applicable |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.
^2In this vulnerability, only the BIG-IP Engineering Hotfixes listed are
affected. This vulnerability does not affect any of the BIG-IP major, minor, or
maintenance releases you obtained from downloads.f5.com.
Security Advisory Recommended Actions
Your BIG-IP system is affected by this vulnerability when all of the following
conditions are met:
o Your BIG-IP system is running an Engineering Hotfix version listed in the
table.
o You configured any of the following three configurations: Remote - LDAP,
Remote - ClientCert LDAP, or Active Directory for remote LDAP
authentication.
o You have more than 1 authentication server configured for remote LDAP
authentication.
To verify your BIG-IP system's version and remote authentication configuration,
perform the following procedures:
Note: If your BIG-IP version is not listed in the vulnerable column of the
table, your system is not affected and you do not have to perform the
subsequent procedures.
o Verify the version of your BIG-IP system.
o Verify if you are using the affected remote LDAP authentication types
o Verify the number of authentication servers set up for remote LDAP
authentication
Verify the version of your BIG-IP system
Impact of procedure: Performing the following procedure should not have a
negative impact on your system.
1. Log in to the TMOS Shell (tmsh) by typing the following command:
tmsh
2. Display your BIG-IP system's version by typing the following command:
show /sys version
When your BIG-IP system version displayed in the output is not one of the
Engineering Hotfix versions listed in the table, your system is not
vulnerable and you do not have to perform further verification.
Verify if you are using the affected remote LDAP authentication types
To verify if you are using any of the following three configurations: Remote -
LDAP, Remote - ClientCert LDAP, or Active Directory for remote LDAP
authentication, perform the following procedure:
Impact of procedure: Performing the following procedure should not have a
negative impact on your system.
1. Log in to tmsh by typing the following command:
tmsh
2. To list your BIG-IP system authentication source, type the following
command:
list /auth source
Your BIG-IP system is not affected if you are not using any of the
following three authentication types: Remote - LDAP, Remote - ClientCert
LDAP or Active Directory.
If you are using Remote - LDAP authentication type, you may observe an
output similar to the following:
auth source {
type ldap
}
If you are using Remote - ClientCert LDAP authentication type, you may
observe an output similar to the following:
auth source {
type cert-ldap
}
If you are using Active Directory authentication type, you may observe an
output similar to the following:
auth source {
type active-directory
}
Verify the number of authentication servers set up for remote LDAP
authentication
To verify the number of authentication servers in your setup, perform the
following procedure:
Impact of procedure: Performing the following procedure should not have a
negative impact on your system.
1. Log in to tmsh by typing the following command:
tmsh
2. To list your system authentication server and LDAP general configuration,
use the following command syntax:
list /auth <authentication type>
In the previous command, the LDAP <authentication type> can be either ldap
or cert-ldap.
For example, if you are using either the Remote - LDAP or Active Directory
authentication type, type the following command:
list /auth ldap
If you are using the cert-ldap authentication type, type the following
command:
list /auth cert-ldap
The following example output displays two servers that are configured using
the cert-ldap authentication type and are affected by this vulnerability:
auth cert-ldap system-auth {
servers { 10.1.1.1 10.1.1.2 }
sso on
}
Mitigation
To mitigate this vulnerability, you can perform any one of the following
procedures:
o Disable any remote LDAP authentication for remote users
o Set up remote LDAP authentication with a single authentication server
o Implement strict access controls based on the source IP address of the
management interface of the BIG-IP system
Disable any remote LDAP authentication for remote users
If you are using any of the following three LDAP authentication types: Remote -
LDAP, Remote - ClientCert LDAP, or Active Directory to disable remote LDAP
authentication for your remote users, perform the following procedure:
Impact of procedure: The BIG-IP system denies access to the Configuration
utility and command line access if you do not already have an alternative User
Directory configured for your environment.
1. Log in to tmsh by typing the following command:
tmsh
2. To list your BIG-IP system authentication source, type the following
command:
list /auth source
If you are using the cert-ldap authentication type, you may observe an
output similar to the following example:
auth source {
type cert-ldap
}
3. To modify your BIG-IP system authentication, use the following command
syntax:
modify auth source type <type>
For example, to change authentication to local, type the following command:
modify auth source type local
Set up remote LDAP authentication with a single authentication server
To set up remote LDAP authentication with a single authentication server, you
need to remove any additional servers in your configuration. To do so, perform
the following procedure:
Impact of procedure: Performing the following procedure should not have a
negative impact on your system.
1. Log in to tmsh by typing the following command:
tmsh
2. To list your system authentication server and LDAP general configuration,
use the following command syntax:
list /auth <authentication type>
In the previous command, <authentication type> can be either ldap or
cert-ldap.
For example, if you are using the cert-ldap authentication type, type the
following command:
list /auth cert-ldap
The following example output displays two servers that are configured using
the cert-ldap authentication type and are affected by this vulnerability:
auth cert-ldap system-auth {
servers { 10.1.1.1 10.1.1.2 }
sso on
}
3. To delete one server from your configuration, use the following command
syntax:
modify /auth <authentication type> system-auth servers delete { <IP address
of server> }
For example, to delete 10.1.1.1 from the existing configuration, type the
following command:
modify /auth cert-ldap system-auth servers delete { 10.1.1.1 }
4. Repeat step 3 until you have only one authentication server in your
configuration.
Implement strict access controls based on the source IP address of the
management interface of the BIG-IP system
You can also mitigate the issue by implementing strict access controls based on
the source IP address of the management interface of your BIG-IP system. You
should implement access restrictions to the BIG-IP system for both the HTTP and
SSH protocols. To do so, refer to K46122561: Restricting access to the
management port using network firewall rules.
Supplemental Information
o K51812227: Understanding Security Advisory versioning
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 - 15.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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