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AUSCERT External Security Bulletin Redistribution
ESB-2022.2490
K83120834: Diffie-Hellman key agreement protocol
vulnerability CVE-2002-20001
20 May 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: BIG-IP
BIG-IQ
F5OS-A
F5OS-C
Traffix SDC
Publisher: F5 Networks
Operating System: Network Appliance
Resolution: Patch/Upgrade
CVE Names: CVE-2002-20001
Original Bulletin:
https://support.f5.com/csp/article/K83120834
Comment: CVSS (Max): 7.5 CVE-2002-20001 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVSS Source: F5 Networks
Calculator: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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K83120834: Diffie-Hellman key agreement protocol vulnerability CVE-2002-20001
Original Publication Date: 19 May, 2022
Security Advisory Description
The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the
client side) to send arbitrary numbers that are actually not public keys, and
trigger expensive server-side DHE modular-exponentiation calculations, aka a D
(HE)ater attack. The client needs very little CPU resources and network
bandwidth. The attack may be more disruptive in cases where a client can
require a server to select its largest supported key size. The basic attack
scenario is that the client must claim that it can only communicate with DHE,
and the server must be configured to allow DHE. (CVE-2002-20001)
Impact
This vulnerability allows remote attackers (from the client side) to send
arbitrary numbers that are actually not public keys, and trigger expensive
server-side DHE modular-exponentiation calculations, also known as a D(HE)ater
attack.
There could be an increase in CPU usage in the affected component. For OpenSSH,
users may observe issues such as a slowdown in SSH connections.
Security Advisory Status
F5 Product Development has assigned IDs 1083281, 1083937, 1093813 (BIG-IP),
IDs 1083281-6, 1083937-1 (BIG-IQ), ID 1086037 (F5OS-A), ID 1086001 (F5OS-C)
and SDC-1752, SDC-1753 (Traffix SDC) 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 |Fixes | |CVSSv3|Vulnerable |
|Product |Branch|known to be|introduced|Severity|score^|component or |
| | |vulnerable^|in | |2 |feature |
| | |1 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
| |17.x |17.0.0 |None | | |apm server |
| | | | | | |components |
| +------+-----------+----------+ | |including, but not |
| | |16.1.0 - | | | |limited to: |
| |16.x |16.1.2 |None | | | |
| | | | | | | o Access Policy |
| +------+-----------+----------+ | | Evaluation |
|BIG-IP | |15.1.0 - | | | | o OAuth |
|(APM) |15.x |15.1.5 |None |High |7.5 | Authorization |
| | | | | | | Server |
| +------+-----------+----------+ | | o SAML IdP |
| | |14.1.0 - | | | | o Privileged User|
| |14.x |14.1.4 |None | | | Access (WebSSH |
| | | | | | | resource SSH |
| +------+-----------+----------+ | | configuration, |
| | |13.1.0 - | | | | LDAPS Proxy, |
| |13.x |13.1.5 |None | | | and Radius |
| | | | | | | Proxy) |
+-----------+------+-----------+----------+--------+------+-------------------+
| |17.x |17.0.0 |None | | | |
| +------+-----------+----------+ | | |
| |16.x |16.1.0 - |None | | | |
| | |16.1.2 | | | |Control plane: |
| +------+-----------+----------+ | |httpd |
|BIG-IP (all|15.x |15.1.0 - |None | | | |
|modules) | |15.1.5 | |High |7.5 |Data plane: |
| +------+-----------+----------+ | |TMM (Client SSL and|
| |14.x |14.1.0 - |None | | |Server SSL profiles|
| | |14.1.4 | | | |with DHE ciphers) |
| +------+-----------+----------+ | | |
| |13.x |13.1.0 - |None | | | |
| | |13.1.5 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
| |17.x |17.0.0 |None | | | |
| +------+-----------+----------+ | | |
| |16.x |16.1.0 - |None | | | |
| | |16.1.2 | | | | |
| +------+-----------+----------+ | | |
|BIG-IP (all|15.x |15.1.0 - |None | | | |
|modules) | |15.1.5 | |Medium |6.2 |OpenSSH |
| +------+-----------+----------+ | | |
| |14.x |14.1.0 - |None | | | |
| | |14.1.4 | | | | |
| +------+-----------+----------+ | | |
| |13.x |13.1.0 - |None | | | |
| | |13.1.5 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
| |8.x |8.0.0 - |None | | | |
|BIG-IQ | |8.2.0 | | | | |
|Centralized+------+-----------+----------+Medium |7.5 |httpd |
|Management |7.x |7.0.0 - |None | | | |
| | |7.1.0 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
| |8.x |8.0.0 - |None | | | |
|BIG-IQ | |8.2.0 | | | | |
|Centralized+------+-----------+----------+Medium |6.2 |OpenSSH |
|Management |7.x |7.0.0 - |None | | | |
| | |7.1.0 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
|F5OS-A |1.x |1.0.0 - |None |Medium |6.2 |OpenSSH |
| | |1.0.1 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
| | |1.3.0 - | | | | |
| | |1.3.2 | | | | |
|F5OS-C |1.x |1.2.0 - |None |Medium |6.2 |OpenSSH |
| | |1.2.2 | | | | |
| | |1.1.0 - | | | | |
| | |1.1.4 | | | | |
+-----------+------+-----------+----------+--------+------+-------------------+
|Traffix SDC|5.x |5.2.0 |None |High |7.5 |WebUI, Tomcat |
| | |5.1.0 | | | |server |
+-----------+------+-----------+----------+--------+------+-------------------+
^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
The following mitigations are currently available. Additional mitigations may
become available in the future as this security advisory is investigated
further.
BIG-IP (control plane)
httpd
Do not use DHE ciphers in the httpd service. For more information, refer to
K02321234: Managing the SSL protocols and ciphers allowed by Configuration
utility.
Note: The httpd service's default cipher-string in the BIG-IP system uses only
ECDHE and RSA for key exchange and is, therefore, not vulnerable by default.
OpenSSH
Beginning in BIG-IP 15.1.x, you can enable Common Criteria mode by enabling the
security.commoncriteria DB variable. To do so, enter the following command on
the bash shell:
tmsh modify sys db security.commoncriteria value true
BIG-IP (data plane)
Configure Client SSL and Server SSL profiles to not use DHE ciphers. Use a
cipher group/suite that does not use DHE ciphers. To do so, refer to the
following articles:
o K01770517: Configuring the cipher strength for SSL profiles (14.x - 16.x)
o K10866411: Creating a custom cipher group using the Configuration utility.
Note: The default Client SSL and Server SSL profiles use DHE ciphers.
BIG-IQ
httpd
Do not use DHE ciphers in the httpd service.
Note: The httpd service's default cipher-string in the BIG-IQ system uses only
ECDHE and RSA for key exchange and is, therefore, not vulnerable by default.
OpenSSH
Beginning in BIG-IQ 8.x, you can enable Common Criteria mode by enabling the
security.commoncriteria DB variable. To do so, enter the following command on
the bash shell:
tmsh modify sys db security.commoncriteria value true
Traffix SDC
WebUI, Tomcat server
Configure Tomcat to not use DHE ciphers. To do so, perform the following:
1. Log in by way of SSH to the EMS machine.
2. Edit the file /opt/traffix/apache-tomcat-8.5.75/conf/server.xml.
3. From the two ciphers= parameters, remove the following values:
TLS_DHE_RSA_WITH_AES_128_SHA256,TLS_DHE_RSA_WITH_AES_128_SHA,TLS_DHE_DSS_WITH_AES_128_SHA256,TLS_DHE_RSA_WITH_AES_256_SHA256,TLS_DHE_DSS_WITH_AES_256_SHA,TLS_DHE_RSA_WITH_AES_256_SHA
4. Restart the Tomcat server.
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 - 17.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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