Define Traffic to Decrypt (PAN-OS & Panorama)

1. Add a new decryption policy rule.

   Select PoliciesDecryption, Add a new decryption policy rule, and give the policy rule a descriptive Name.
2. Configure the decryption rule to match to traffic based on network and policy objects:

   • Firewall security zones—Select Source or Destination and match to traffic based on the Source Zone or Destination Zone.
   • IP addresses, address objects, or address groups—Select Source or Destination to match to traffic based on the Source Address or the Destination Address. Alternatively, select Negate to exclude the source address list from decryption.
   • Users—Select Source and set the Source User for whom to decrypt traffic. You can decrypt specific user or group traffic or decrypt traffic for certain types of users, such as unknown users or pre-logon users (users who are connected to GlobalProtect but are not yet logged in).
   • Ports and protocols—Select Service/URL Category to set the rule to match to traffic based on service. By default, the policy rule is set to decrypt Any traffic on TCP and UDP ports. You can Add a service or a service group, and optionally set the rule to application-default to match to applications only on the application default ports.

   The application-default setting can be useful when you create a policy-based decryption exclusion. You can exclude applications running on their default ports from decryption, while continuing to decrypt the same applications when they are detected on nonstandard ports.

   • URLs and URL categories—Select Service/URL Category and decrypt traffic based on:
     • An externally hosted list of URLs that the NGFW retrieves for policy-enforcement (see ObjectsExternal Dynamic Lists).
     • Palo Alto Networks predefined URL categories, which make it easy to decrypt entire categories of allowed traffic. This option is also useful when you create policy-based decryption exclusions because you can exclude sensitive sites by category instead of individually. For example, although you can create a custom URL category to group sites that you do not want to decrypt, you can also exclude financial or healthcare-related sites from decryption based on the predefined Palo Alto Networks URL categories. In addition, you can block risky URL categories and create comfort pages to communicate the reason the sites are blocked, or enable users to opt out of SSL decryption.
       You can use the predefined high-risk and medium-risk URL categories to create a decryption policy rule that decrypts all high-risk and medium-risk URL traffic. Place the rule at the bottom of the rulebase (all decryption exceptions must be above this rule so that you don’t decrypt sensitive information) as a safety net to ensure that you decrypt and inspect all risky traffic. However, if high-risk or medium-risk sites to which you allow access contain personally identifiable information (PII) or other sensitive information that you don’t want to decrypt, either block those sites to avoid allowing encrypted risky traffic while also avoiding privacy issues or create a no- decrypt policy rule to handle the sensitive traffic.
     • Custom URL categories (see ObjectsCustom ObjectsURL Category). For example, you can create a custom URL category to specify a group of sites you need to access for business purposes but that don't support the safest protocols and algorithms, and then apply a customized decryption profile to allow the weaker protocols and algorithms for just those sites (that way, you don’t decrease security by downgrading the decryption profile you use for most sites).
3. Set the rule to either decrypt matching traffic or to exclude matching traffic from decryption.

   Select Options and set the policy rule Action:

   To decrypt matching traffic:

   1. Set the Action to Decrypt.
   2. Select the Type of decryption:

      • SSL Forward Proxy.
      • SSL Inbound Inspection. Then, Add one or more Certificates for the destination internal server of the inbound SSL traffic. SSL Inbound Inspection policy rules support a maximum of 12 certificates.
        You can configure a decryption policy rule to decrypt SSL/TLS traffic bound for an internal server that hosts multiple domains, each domain with its own certificate. The NGFW negotiates SSL/TLS connections using the certificate in your policy rule that matches the one the server presents for the requested URL.
        To update certificates for protected internal servers without incurring downtime, renew or obtain a new server certificate before it expires or otherwise becomes invalid. Then, import the certificate and private key onto your NGFW or Strata Cloud Manager, add it to an SSL Inbound Inspection policy rule before installing the same certificate onto your web server. Updating your policy rule with a new certificate while another is active on your web server prepares the NGFW to decrypt traffic to the server regardless of the certificate in use. Configure SSL Inbound Inspection describes this process further.

        (Panorama ^™) Support for multiple certificates in SSL Inbound Inspection policy rules is unavailable in PAN-OS^® versions earlier than PAN-OS 10.2. If you push an SSL Inbound Inspection policy rule with multiple certificates from a Panorama management server running PAN-OS 10.2 to a NGFW running an earlier version, the policy rule on the managed NGFW inherits only the first certificate from the alphabetically sorted list of certificates.

        Before pushing your decryption policy rule from Panorama, we recommend you set up different templates or device groups for NGFWs running PAN-OS 10.1 and earlier to ensure you push the correct policy rule and certificate to the appropriate NGFWs.
      • SSH Proxy.

   To exclude matching traffic from decryption:

   Set the Action to No Decrypt.

   Apply a no-decryption profile to undecrypted traffic to block sessions with expired certificates and untrusted issuers. Just because you don't decrypt the traffic does not mean you should let just any undecrypted traffic on your network. Server certificate checks help with this.
4. (Optional) Select a Decryption Profile to perform additional checks on traffic that matches the policy rule.

   For example, set up certificate revocation status verification to ensure that server certificates are valid or block sessions using unsupported protocols or ciphers.

   To create a decryption profile, select ObjectsDecryption Profile.

   Although optional, always apply a decryption profile to decryption policy rules to protect your network against encrypted threats. You can’t protect yourself against threats you can’t see.

   1. Create a decryption policy rule or open an existing rule to modify it.
   2. Select Options and select a Decryption Profile to block and control various aspects of the traffic matched to the rule.

      The profile rule settings applied to matching traffic depends on the policy rule Action (Decrypt or No Decrypt) and the policy rule Type (SSL Forward Proxy, SSL Inbound Inspection, or SSH Proxy). This allows you to use the different decryption profiles with different types of decryption policy rules that apply to different types of traffic and users.
   3. Click OK.
5. Configure decryption logging (configure whether to log both successful and unsuccessful TLS handshakes and configure decryption log forwarding).
6. Click OK to save the rule.
7. Commit your changes.
8. Test your decryption configuration.
9. Choose your next step...

   • Configure SSL Forward Proxy.
   • Configure SSL Inbound Inspection.
   • Configure SSH Proxy.
   • Create policy-based decryption exclusions for traffic you choose not to decrypt and add sites that break decryption for technical reasons such as pinned certificates or mutual authentication to the SSL decryption exclusion list.