BigIP F5 – Poodle Vulnerability

Poodle was initially targeted against SSLv3. Quite a few websites fixed this issue at the server and client side by disabling SSLv3. There is a variation of Poodle for TLS with the following CVE ID: CVE-2014-8730. For a brief description of the issue: Poodle on TLS

This is known to affect load balancers like F5. F5 recommends a code upgrade. As of now (Dec 09, 2014), it is recommended that the code is upgraded to at least 10.2.4 with HotFix 10 if you are running 10.x code version and one of the 11.x code versions that is not vulnerable as per F5 documentation: SOL15882

F5 has stated that the code upgrade is the best possible option available. 

BigIP F5:

If you are running F5 LTM on 11.x code version, using 11.5.1 with HF6 and above is recommended.

If you are running F5 LTM on 10.x code version and want to stay in 10.x code version, you would have to perform the following tasks in order to have a “A-” rating in Qualys SSL test:

  • Upgrade code to 10.2.4 HF10
  • After code upgrade to 10.2.4 HF10, complete the following steps in order to remove RC4.
(tmos.ltm)# create profile client-ssl PARENT-SSL-SECURE ciphers 'HIGH:MEDIUM:!SSLv3:!RC4'

(tmos.ltm)# modify profile client-ssl CUSTOM-CLIENT-SSL defaults-from PARENT-SSL-PROFILE-SECURE

Qualys Rating is “B” after code upgrade and “A-” after performing code upgrade and removing RC4.

After making the code upgrade & removing RC4 cipher, it is recommended that you test your site for any vulnerabilities at the Qualys Site.

The above commands will create a “Parent” SSL Client profile – “PARENT-SSL-SECURE” that will disable SSLv3, RC4 and order the ciphers from High to Medium strength. Please, note that any client initiating connection on SSLv3 will be dropped. Usually clients running Windows XP and IE6 will initiate SSLv3 connections.

In order to know the total SSLv3 connections, you can run this command:

(tmos.ltm)# show profile client-ssl CUSTOM-CLIENT-SSL | grep Protocol
 SSL Protocol Version 2                       0
 SSL Protocol Version 3                      156
 TLS Protocol Version 1.0                   16.1K
 TLS Protocol Version 1.2                   11.6K
 DTLS Protocol Version 1                      0

Based on the above output, it can be seen that the client SSL profile configured on the Virtual Server handling SSL traffic has received 156 SSLv3 connection requests.

The stats can be cleared using this command:

(tmos.ltm)# reset-stats profile client-ssl

(tmos.ltm)# show profile client-ssl CUSTOM-CLIENT-SSL | grep Protocol
 SSL Protocol Version 2                       0
 SSL Protocol Version 3                       0
 TLS Protocol Version 1.0                     0
 TLS Protocol Version 1.2                   11.6K
 DTLS Protocol Version 1                      0

Note: The “reset-stats” command will NOT clear the stats for TLS1.2  in 10.2.3 code version. F5 is aware of this bug. I was able to clear the stats for 10.2.4 code version. I am not sure if this bug exists for 10.2.3 and lower code versions.

The cipher suite that is being utilized, after the change can be identified by running the following command in bash:

[root@lbal1:Active] config # tmm --clientciphers 'HIGH:MEDIUM:!SSLv3:!SSLv2:!RC4:!COMPAT:!EXP'



After making the above changes, some of the older browsers may not be able to connect to your website on HTTPS as the older browsers don’t support TLS1.2. For a list of browsers and supported protocols, see here.

Having dealt with SSL/TLS vulnerabilities, it looks like TLS1.2 with Ephemeral Diffie-Hellman is the most secure current version. Anything before TLS1.1 would be insecure and would have to be avoided, if possible. The main problem is that there are quite a few client browsers that are just incompatible with TLS1.2 and this has to be factored before making any changes.

GHOST Vulnerability:

This is a recent vulnerability – CVE-2015-0235

According to SOL16057, if you want to stay with 10.x code version on F5 LTM, it is better to use 10.2.4 + HF11. For 11.x code version, use at least 11.5.1 + HF8.


For a great Qualys grade see the following link.