SOL01471335 - BIND vulnerability CVE-2016-2848

Vulnerability 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 theVersions known to be not vulnerable 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.

Mitigation

To mitigate this vulnerability, you can use the DNS Caching and DNS Express features instead of BIND. Additionally, to mitigate the issue on the management IP address, restrict access for that IP address to trusted hosts only.

To mitigate the issue on the self IP address, prevent access to port 53 on the self IP address. If your self IP address is configured to use the default allow setting, you can remove that port from the list of the default allowed services.

• Ensuring that TCP/UDP port 53 is not allowed as a default service (allow-service default)
• Disabling the Use BIND Server on BIG-IP option in the DNS profile

Ensuring that TCP/UDP port 53 is not allowed as a default service (allow-service default)

1. Log in to the Traffic Management Shell (tmsh) by typing the following command:

tmsh

2. List the default services allowed by the allow-service defaultsetting, by typing the following command:

list net self-allow

The command output appears similar to the following example:

net self-allow {
defaults {
ospf:any
tcp:domain
tcp:f5-iquery
tcp:https
tcp:snmp
tcp:ssh
udp:520
udp:cap
udp:domain
udp:f5-iquery
udp:snmp
}
}

3. If TCP port 53 (tcp:53 or tcp:domain) or UDP port 53 (udp:53 or udp:domain) are listed as a default allowed port, delete the entries by typing the following command:

modify net self-allow defaults delete { tcp:domain udp:domain }

4. Save the configuration by typing the following command:

save sys config

Disabling the Use BIND Server on BIG-IP option in the DNS profile

Important: Disabling the BIND server can affect DNS configurations that use BIND as a fallback method (return to DNS) for resolution.

1. Log in to the Configuration utility.
2. Navigate to Local Traffic >** Profiles** >** Services** >DNS.
3. Select the applicable DNS profile.
4. For the Use BIND Server on BIG-IP option, selectDisabled. 5. ClickFinished.

BIG-IP GTM/Link Controller

• Determining if any listener addresses share a self IP address (BIG-IP GTM/Link Controller)
• Choosing a load balancing method other than Return to DNS for the GTM pool (BIG-IP GTM)

Determining if any listener addresses share a self IP address (BIG-IP GTM/Link Controller)

Listener addresses that share a self IP address will expose the system to this vulnerability. To determine if you have configured a listener address to share a self IP address, run the following commands:

• tmsh list /net self address
• tmsh list /gtm listener address

If you have configured a listener address to share a self IP address, you should reconfigure the address to use a unique IP address.

Choosing a load balancing method other than Return to DNS for the GTM pool (BIG-IP GTM)

Important: If DNS Express is not configured, BIG-IP GTM or Link Controller systems will respond to A, AAAA, and CNAME type DNS record queries only. Queries for other types of records, such as NS or MX, will fail.

1. Log in to the Configuration utility.
2. Navigate to DNS>GSLB>** Pools.** 3. From thePool List menu, select the applicable pool.
3. Click Members.
4. Choose a load balancing method other than Return to DNS.
5. Click Update.

Supplemental Information

• SOL9970: Subscribing to email notifications regarding F5 products
• SOL9957: Creating a custom RSS feed to view new and updated documents
• SOL4602: Overview of the F5 security vulnerability response policy
• SOL4918: Overview of the F5 critical issue hotfix policy
• SOL167: Downloading software and firmware from F5
• SOL13123: Managing BIG-IP product hotfixes (11.x - 12.x)
• SOL9502: BIG-IP hotfix matrix