Enable DNS Security

1. Activate Subscription Licenses.
2. Verify that the paloalto-dns-security App-ID in your security policy is configured to enable traffic from the DNS security cloud security service.
   If your firewall deployment routes your management traffic though an Internet-facing perimeter firewall configured to enforce App-ID security policies, you must allow the App-IDs on the perimeter firewall; failure to do so will prevent DNS security connectivity.
3. Configure DNS Security signature policy settings to send malware DNS queries to the defined sinkhole.
   If you use an external dynamic list as a domain allow list, it does not have precedence over the DNS Security domain policy actions. As a result, when there is a domain match to an entry in the EDL and a DNS Security domain category, the action specified under DNS Security is still applied, even when the EDL is explicitly configured with an action of Allow. If you want to add DNS domain exceptions, you can configure an EDL with an Alert action.
   1. Select ObjectsSecurity ProfilesAnti-Spyware.
   2. Create or modify an existing profile, or select one of the existing default profiles and clone it.
   3. Name the profile and, optionally, provide a description.
   4. Select the DNS Signatures > Policies & Settings tab.
   5. If the Palo Alto Networks DNS Security source is not present, click Add and select it from the list.
   6. Select an action to be taken when DNS lookups are made to known malware sites for the DNS Security signature source under the Action on DNS Queries column. The options are alert, allow, block, and sinkhole. Verify that the action is set to sinkhole.
      You can fully bypass DNS traffic inspection by configuring your Action on DNS Queries setting to allow.
   7. (Optional) In the Packet Capture drop-down, select single-packet to capture the first packet of the session or extended-capture to set between 1-50 packets. You can then use the packet captures for further analysis.
   8. In the DNS Sinkhole Settings section, verify that Sinkhole is enabled. For your convenience, the default Sinkhole address (sinkhole.paloaltonetworks.com) is set to access a Palo Alto Networks server. Palo Alto Networks can automatically refresh this address through content updates.
      If you want to modify the Sinkhole IPv4 or Sinkhole IPv6 address to a local server on your network or to a loopback address, see Configure the Sinkhole IP Address to a Local Server on Your Network.
   9. Click OK to save the Anti-Spyware profile.

4. Attach the Anti-Spyware profile to a Security policy rule.
   1. Select PoliciesSecurity.
   2. Select or create a Security Policy Rule.
   3. On the Actions tab, select the Log at Session End check box to enable logging.
   4. In the Profile Setting section, click the Profile Type drop-down to view all Profiles. From the Anti-Spyware drop-down and select the new or modified profile.
   5. Click OK to save the policy rule.
5. Test that the policy action is enforced.
   1. Access the following test domains to verify that the policy action for a given threat type is being enforced:
      • Malware—test-malware.testpanw.com
      • C2—test-c2.testpanw.com
      • DGA—test-dga.testpanw.com
      • DNS Tunneling—test-dnstun.testpanw.com
   2. To monitor the activity on the firewall:
      1. Select ACC and add a URL Domain as a global filter to view the Threat Activity and Blocked Activity for the domain you accessed.
      2. Select MonitorLogsThreat and filter by (action eq sinkhole) to view logs on sinkholed domains.
6. Identify Infected Traffic Hosts in the Traffic Logs
7. (Optional) Add domain signature exceptions in cases where false-positives occur.
   1. Select ObjectsSecurity ProfilesAnti-Spyware.
   2. Select a profile to modify.
   3. Add or modify the Anti-Spyware profile from which you want to exclude the threat signature, and select DNS Signatures > Exceptions.
   4. Search for a DNS signature to exclude by entering the name or FQDN.
   5. Select the DNS Threat ID for the DNS signature that you want to exclude from enforcement.
   6. Click OK to save your new or modified Anti-Spyware profile.

8. (Optional) Configure the DNS signature lookup timeout setting. If the firewall is unable to retrieve a signature verdict in the allotted time due to connectivity issues, the request, including all subsequent DNS responses, are passed through. You can check the average latency to verify that the requests fall within the configured period. If the average latency exceeds the configured period, consider updating the setting to a value that is higher than the average latency to prevent requests from timing out.
   1. In the CLI, issue the following command to view the average latency.

      show dns-proxy dns-signature
      counters

      The default timeout is 100 milliseconds.
   2. Scroll down through the output to the latency section under the Signature query API heading and verify that the average latency falls within the defined timeout period. This latency indicates the amount of time it takes, on average, to retrieve a signature verdict from the DNS security service. Additional latency statistics for various latency periods can be found below the averages.

      Signature query API:
      	 .
      		.
      		.
      	    [latency   ] :
              max    1870 (ms)  min    16(ms)  avg    27(ms)
                50 or less : 47246
                100 or less : 113
                200 or less : 25
                400 or less : 15
                       else : 21

   3. If the average latency is consistency above the default timeout value, you can raise the setting so that the requests fall within a given period. Select Device > Content-ID and update the Realtime Signature Lookup setting.
   4. Commit the changes.