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    Policy Object: Applications
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    Network Security

    Policy Object: Applications

    Table of Contents

    Policy Object: Applications

    Exercise granular policy control over applications to minimize the range of unidentified traffic on your network, thereby reducing the attack surface.
    Where Can I Use This?
    What Do I Need?
    • NGFW (Cloud Managed)
    • NGFW (PAN-OS & Panorama Managed)
    • Prisma Access (Cloud Management)
    • Prisma Access (Panorama Managed)
    Check for any license or role requirements for the products you're using.
    Your network traffic is automatically classified into applications that you can use to build a versatile Security policy based on your business needs (for example, allow Slack messages but block file transfers). The Applications object lists various attributes of each application definition, such as the application’s relative security risk (1 to 5). The risk value is based on criteria such as whether the application can share files, is prone to misuse, or tries to evade being detected. Higher values indicate higher risk.
    To configure this and any other Object settings, go to:
    • Manage
      Configuration
      NGFW and
      Prisma Access
      Objects
       on Cloud Managed deployments, and select the object you want to configure.
    • Objects
       on PAN-OS and Panorama Managed deployments, and select the object you want to configure from the panel on the left.
    On the application page, you can:
    • Learn about applications, including their behavioral characteristics and risk level. This list includes over 3000 well-known and commercially available applications.
    • Create custom applications based on application characteristics or behavior. Create custom applications to classify internal applications (a custom payroll app), special interest applications (an annual sports event), or a nested application (classify a function separately from the parent application, like Facebook’s Words with Friends). Custom applications can be global or they can be applied only to specific mobile user, remote network, and service connection locations (the
      Locations
       column indicates the deployment types that can use the custom app).

    Applications Fields

    Here are the various applications fields. Custom applications and Palo Alto® Networks applications might display some or all of these fields.
    Application Details
    Description
    Name
    Name of the application.
    Description
    Description of the application (up to 255 characters).
    Additional Information
    Links to web sources (Wikipedia, Google, and Yahoo!) that contain additional information about the application.
    Standard Ports
    Ports that the application uses to communicate with the network.
    Depends on
    A list of other applications that are required for this application to run. When creating a security rule to allow the selected application, you must also be sure that you're allowing any other applications that the application depends on.
    Implicitly Uses
    Other applications that the selected application depends on but that you don't need to add to your Security rules to allow the selected application because those applications are supported implicitly.
    Previously Identified As
    For a new App-ID, or App-IDs that are changed, this indicates what the application was previously identified as. This helps you assess whether policy changes are required based on changes in the application. If an App-ID is disabled, sessions associated with that application will match the security rule as the previously identified as application. Similarly, disabled App-IDs will appear in logs as the application they were previous identified as.
    Deny Action
    App-IDs are developed with a default deny action that dictates the response when the application is included in a Security security rule with a deny action. The default deny action can specify either a silent drop or a TCP reset. You can override this default action in the Security policy.
    Characteristics
    Evasive
    Uses a port or protocol for something other than its originally intended purpose with the hope that it won't get detected.
    Excessive Bandwidth
    Consumes at least 1 Mbps regularly through normal use.
    Prone to Misuse
    Often used for nefarious purposes or is easily set up to expose more than the user intended.
    SaaS
    Software as a Service (SaaS) is characterized as a service where the software and infrastructure are owned and managed by the application service provider but where you retain full control of the data, including who can create, access, share, and transfer the data.
    Keep in mind that in the context of how an application is characterized, SaaS applications differ from web services. Web services are hosted applications where either the user does not own the data (for example, Pandora) or where the service is primarily comprised of sharing data fed by many subscribers for social purposes (for example, LinkedIn, Twitter, or Facebook).
    Capable of File Transfer
    It has the capability to transfer a file from one system to another over a network.
    Tunnels Other Applications
    It's able to transport other applications inside its protocol.
    Used by Malware
    Malware has been known to use the application for propagation, attack, or data theft, or is distributed with malware.
    Has Known Vulnerabilities
    Has publicly reported vulnerabilities.
    Pervasive
    Likely has more than 1,000,000 users.
    Continue Scanning for Other Applications
    Continue to try to match against other application signatures. If you don't select this option, additional application matches won't be sought out after the first matching signature.
    SaaS Characteristics
    Data Breaches
    Applications that may have released secure information to an untrusted source within the past three years.
    Poor Terms of Service
    Applications with unfavorable terms of service that can compromise enterprise data.
    No Certifications
    Applications lacking current compliance with industry programs or certifications such as SOC1, SOC 2, SSAE16, PCI, HIPAA, FINRAA, or FedRAMP.
    Poor Financial Viability
    Applications with the potential to be out of business within the next 18 to 24 months.
    No IP Restrictions
    Applications without IP-based restrictions for user access.
    Classification
    Category
    The application category will be one of the following:
    • business-systems
    • collaboration
    • general-internet
    • media
    • networking
    • unknown
    Subcategory
    The subcategory in which the application is classified. Different categories have different subcategories associated with them. For example, subcategories in the collaboration category include email, file sharing, instant-messaging, Internet-conferencing, social-business, social-networking, voip-video, and web-posting. Whereas subcategories in the business-systems category include auth-service, database, erp-crm, general-business, management, office-programs, software-update, and storage-backup.
    Technology
    The application technology will be one of the following:
    • client-server: An application that uses a client-server model where one or more clients communicate with a server in the network.
    • network-protocol: An application that is used for system-to-system communication that facilitates network operation. This includes most of the IP protocols.
    • peer-to-peer: An application that communicates directly with other clients to transfer information instead of relying on a central server to facilitate the communication.
    • browser-based: An application that relies on a web browser to function.
    Risk
    Assigned risk of the application.
    Tags
    Tags assigned to an application.
    Edit tags to add or remove tags for an application.
    Options
    Session Timeout
    The period of time, in seconds, required for the application to time out due to inactivity (range is 1-604800 seconds). This timeout is for protocols other than TCP or UDP. For TCP and UDP, refer to the next rows in this table.
    TCP Timeout (seconds)
    Timeout, in seconds, for terminating a TCP application flow (range is 1-604800).
    A value of 0 indicates that the global session timer will be used, which is 3600 seconds for TCP.
    UDP Timeout (seconds):
    Timeout, in seconds, for terminating a UDP application flow (range is 1-604800 seconds).
    TCP Half Closed (seconds)
    Maximum length of time, in seconds, that a session remains in the session table between receiving the first FIN packet and receiving the second FIN packet or RST packet. If the timer expires, the session is closed (range is 1-604800).
    Default: If this timer isn't configured at the application level, the global setting is used.
    If this value is configured at the application level, it overrides the global TCP Half Closed setting.
    TCP Time Wait (seconds)
    Maximum length of time, in seconds, that a session remains in the session table after receiving the second FIN packet or an RST packet. If the timer expires, the session is closed (range is 1-600).
    Default: If this timer isn't configured at the application level, the global setting is used.
    If this value is configured at the application level, it overrides the global TCP Time Wait setting.
    App-ID Enabled
    Indicates whether the App-ID is enabled or disabled. If an App-ID is disabled, traffic for that application will be treated as the Previously Identified As App-ID in both Security policy and in logs. For applications added after content release version 490, you have the ability to disable them while you review the impact on Security policy of the new app. After reviewing the security rule, you may choose to enable the App-ID. You also have the ability to disable an application that you have previously enabled. On a multi-vsys, you can disable App-IDs separately in each virtual system.

    Create a Custom Application

    Cloud Managed

    Exercise granular policy control over applications to minimize the range of unidentified traffic on your network, thereby reducing the attack surface.
    To safely enable applications you must classify all traffic, across all ports, all the time. With App-ID, the only applications that are typically classified as unknown traffic—tcp, udp or non-syn-tcp—in the ACC and the Traffic logs are commercially available applications that have not yet been added to App-ID, internal or custom applications on your network, or potential threats.
    If you're seeing unknown traffic for a commercial application that does not yet have an App-ID, you can submit a request for a new App-ID here: http://researchcenter.paloaltonetworks.com/submit-an-application/.
    To ensure that your internal custom applications don't show up as unknown traffic, create a custom application. You can then exercise granular policy control over these applications in order to minimize the range of unidentified traffic on your network, thereby reducing the attack surface. Creating a custom application also allows you to correctly identify the application in the ACC and Traffic logs, which enables you to audit/report on the applications on your network.
    To create a custom application, you must define the application attributes: its characteristics, category, and sub-category, risk, port, timeout. In addition, you must define patterns or values that the your configuration can use to match to the traffic flows themselves (the signature). Finally, you can attach the custom application to a Security rule that allows or denies the application (or add it to an application group or match it to an application filter). You can also create custom applications to identify ephemeral applications with topical interest, such as ESPN3-Video for world cup soccer or March Madness.
    In order to collect the right data to create a custom application signature, you'll need a good understanding of packet captures and how datagrams are formed. If the signature is created too broadly, you might inadvertently include other similar traffic; if it's defined too narrowly, the traffic will evade detection if it does not strictly match the pattern.
    Custom applications are stored in a separate database on the firewall and this database isn't impacted by the weekly App-ID updates.
    The supported application protocol decoders that enable the firewall to detect applications that may be tunneling inside of the protocol include the following as of content release version 609: FTP, HTTP, IMAP, POP3, SMB, and SMTP.
    The following is a basic example of how to create a custom application.
    1. Gather information about the application that you will be able to use to write custom signatures.
      To do this, you must have an understanding of the application and how you want to control access to it. For example, you may want to limit what operations users can perform within the application (such as uploading, downloading, or live streaming). Or you may want to allow the application, but enforce QoS policing.
      • Capture application packets so that you can find unique characteristics about the application on which to base your custom application signature. One way to do this is to run a protocol analyzer, such as Wireshark, on the client system to capture the packets between the client and the server. Perform different actions in the application, such as uploading and downloading, so that you will be able to locate each type of session in the resulting packet captures (PCAPs).
      • Because the firewall by default takes packet captures for all unknown traffic, if the firewall is between the client and the server you can view the packet capture for the unknown traffic directly from the Traffic log.
      • Use the packet captures to find patterns or values in the packet contexts that you can use to create signatures that will uniquely match the application traffic. For example, look for string patterns in HTTP response or request headers, URI paths, or hostnames. For information on the different string contexts you can use to create application signatures and where you can find the corresponding values in the packet, refer to Creating Custom Threat Signatures.
    2. Add the custom application.
      1. Select
        Manage
        Configuration
        NGFW and Prisma Access
        Objects
        Application
        Applications
         and select
        Add Application
        .
      2. On the
        Configuration
         tab, enter a
        Name
         and a
        Description
         for the custom application that will help other administrators understand why you created the application.
      3. Define the application Properties and Characteristics.
    3. Define details about the application, such as the underlying protocol, the port number the application runs on, the timeout values, and any types of scanning you want to be able to perform on the traffic.
      On the
      Advanced
       tab, define settings that will allow the firewall to identify the application protocol:
      • Specify the default ports or protocol that the application uses.
      • Specify the session timeout values. If you don’t specify timeout values, the default timeout values will be used.
      • Indicate any type of additional scanning you plan to perform on the application traffic.
      For example, to create a custom TCP-based application that runs over SSL, but uses port 4443 (instead of the default port for SSL, 443), you would specify the port number. By adding the port number for a custom application, you can create security rules that use the default port for the application rather than opening up additional ports on the firewall. This improves your security posture.
    4. Define the criteria that the firewall will use to match the traffic to the new application.
      You will use the information you gathered from the packet captures to specify unique string context values that the firewall can use to match patterns in the application traffic.
      1. On the
        Signatures
         tab, click
        Add
         and define a
        Signature Name
         and optionally a
        Comment
         to provide information about how you intend to use this signature.
      2. Specify the
        Scope
         of the signature: whether it matches to a full
        Session
         or a single
        Transaction
        .
      3. Specify conditions to define signatures by clicking
        Add And Condition
         or
        Add Or Condition
        .
      4. Select an
        Operator
         to define the type of match conditions you will use:
        Pattern Match
         or
        Equal To
        .
        • If you selected
          Pattern Match
          , select the
          Context
           and then use a regular expression to define the
          Pattern
           to match the selected context. Optionally, click
          Add
           to define a qualifier/value pair. The
          Qualifier
           list is specific to the
          Context
           you chose.
        • If you selected
          Equal To
          , select the
          Context
           and then use a regular expression to define the
          Position
           of the bytes in the packet header to use match the selected context. Choose from
          first-4bytes
           or
          second-4bytes
          . Define the 4-byte hex value for the
          Mask
           (for example, 0xffffff00) and
          Value
           (for example, 0xaabbccdd).
        For example, if you're creating a custom application for one of your internal applications, you could use the
        ssl-rsp-certificate Context
         to define a pattern match for the certificate response message of an SSL negotiation from the server and create a
        Pattern
         to match the Common Name of the server in the message as shown here:
      5. Repeat steps 4.c and 4.d for each matching condition.
      6. If the order in which your configuration attempts to match the signature definitions is important, make sure the
        Ordered Condition Match
         check box is selected and then order the conditions so that they are evaluated in the appropriate order. Select a condition or a group and select the Up Arrow or Down Arrow. You can't move conditions from one group to another.
      7. Select
        Add
         to save the signature definition.
    5. Save
       the application.
    6. Validate that traffic matches the custom application as expected.
      1. Select
        Manage
        Configuration
        NGFW and Prisma Access
        Security Services
        Security Policy
         and select
        Add Rule
         add a Security security rule to allow the new application.
      2. Run the application from a client system and then check the Traffic logs (
        Incidents & Alerts
        Log Viewer
        Firewall/Traffic
        ) to make sure that you see traffic matching the new application (and that it's being handled per your policy rule).

    PAN-OS & Panorama

    Exercise granular policy control over applications to minimize the range of unidentified traffic on your network, thereby reducing the attack surface.
    To safely enable applications you must classify all traffic, across all ports, all the time. With App-ID, the only applications that are typically classified as unknown traffic—tcp, udp or non-syn-tcp—in the ACC and the Traffic logs are commercially available applications that have not yet been added to App-ID, internal or custom applications on your network, or potential threats.
    If you're seeing unknown traffic for a commercial application that does not yet have an App-ID, you can submit a request for a new App-ID here: http://researchcenter.paloaltonetworks.com/submit-an-application/.
    To ensure that your internal custom applications don't show up as unknown traffic, create a custom application. You can then exercise granular policy control over these applications to minimize the range of unidentified traffic on your network, thereby reducing the attack surface. Creating a custom application also allows you to correctly identify the application in the ACC and Traffic logs, which enables you to audit/report on the applications on your network.
    To create a custom application, you must define the application attributes: its characteristics, category, and sub-category, risk, port, timeout. In addition, you must define patterns or values that the firewall can use to match to the traffic flows themselves (the signature). Finally, you can attach the custom application to a Security rule that allows or denies the application (or add it to an application group or match it to an application filter). You can also create custom applications to identify ephemeral applications with topical interest, such as ESPN3-Video for world cup soccer or March Madness.
    In order to collect the right data to create a custom application signature, you'll need a good understanding of packet captures and how datagrams are formed. If the signature is created too broadly, you might inadvertently include other similar traffic; if it's defined too narrowly, the traffic will evade detection if it does not strictly match the pattern.
    Custom applications are stored in a separate database on the firewall and this database isn't impacted by the weekly App-ID updates.
    The supported application protocol decoders that enable the firewall to detect applications that may be tunneling inside of the protocol include the following as of content release version 609: FTP, HTTP, IMAP, POP3, SMB, and SMTP.
    The following is a basic example of how to create a custom application.
    1. Gather information about the application that you will be able to use to write custom signatures.
      To do this, you must have an understanding of the application and how you want to control access to it. For example, you may want to limit what operations users can perform within the application (such as uploading, downloading, or live streaming). Or you may want to allow the application, but enforce QoS policing.
      • Capture application packets so that you can find unique characteristics about the application on which to base your custom application signature. One way to do this is to run a protocol analyzer, such as Wireshark, on the client system to capture the packets between the client and the server. Perform different actions in the application, such as uploading and downloading, so that you will be able to locate each type of session in the resulting packet captures (PCAPs).
      • Because the firewall by default takes packet captures for all unknown traffic, if the firewall is between the client and the server you can view the packet capture for the unknown traffic directly from the Traffic log.
      • Use the packet captures to find patterns or values in the packet contexts that you can use to create signatures that will uniquely match the application traffic. For example, look for string patterns in HTTP response or request headers, URI paths, or hostnames. For information on the different string contexts you can use to create application signatures and where you can find the corresponding values in the packet, refer to Creating Custom Threat Signatures.
    2. Add the custom application.
      1. Select
        Objects
        Applications
         and click
        Add
        .
      2. On the
        Configuration
         tab, enter a
        Name
         and a
        Description
         for the custom application that will help other administrators understand why you created the application.
      3. (
        Optional
        ) Select
        Shared
         to create the object in a shared location for access as a shared object in Panorama or for use across all virtual systems in a multiple virtual system firewall.
      4. Define the application Properties and Characteristics.
    3. Define details about the application, such as the underlying protocol, the port number the application runs on, the timeout values, and any types of scanning you want to be able to perform on the traffic.
      On the
      Advanced
       tab, define settings that will allow the firewall to identify the application protocol:
      • Specify the default ports or protocol that the application uses.
      • Specify the session timeout values. If you don’t specify timeout values, the default timeout values will be used.
      • Indicate any type of additional scanning you plan to perform on the application traffic.
      For example, to create a custom TCP-based application that runs over SSL, but uses port 4443 (instead of the default port for SSL, 443), you would specify the port number. By adding the port number for a custom application, you can create security rules that use the default port for the application rather than opening up additional ports on the firewall. This improves your security posture.
    4. Define the criteria that the firewall will use to match the traffic to the new application.
      You will use the information you gathered from the packet captures to specify unique string context values that the firewall can use to match patterns in the application traffic.
      1. On the
        Signatures
         tab, click
        Add
         and define a
        Signature Name
         and optionally a
        Comment
         to provide information about how you intend to use this signature.
      2. Specify the
        Scope
         of the signature: whether it matches to a full
        Session
         or a single
        Transaction
        .
      3. Specify conditions to define signatures by clicking
        Add And Condition
         or
        Add Or Condition
        .
      4. Select an
        Operator
         to define the type of match conditions you will use:
        Pattern Match
         or
        Equal To
        .
        • If you selected
          Pattern Match
          , select the
          Context
           and then use a regular expression to define the
          Pattern
           to match the selected context. Optionally, click
          Add
           to define a qualifier/value pair. The
          Qualifier
           list is specific to the
          Context
           you chose.
        • If you selected
          Equal To
          , select the
          Context
           and then use a regular expression to define the
          Position
           of the bytes in the packet header to use match the selected context. Choose from
          first-4bytes
           or
          second-4bytes
          . Define the 4-byte hex value for the
          Mask
           (for example, 0xffffff00) and
          Value
           (for example, 0xaabbccdd).
        For example, if you're creating a custom application for one of your internal applications, you could use the
        ssl-rsp-certificate Context
         to define a pattern match for the certificate response message of an SSL negotiation from the server and create a
        Pattern
         to match the Common Name of the server in the message as shown here:
      5. Repeat steps 4.c and 4.d for each matching condition.
      6. If the order in which the firewall attempts to match the signature definitions is important, make sure the
        Ordered Condition Match
         check box is selected and then order the conditions so that they are evaluated in the appropriate order. Select a condition or a group and click
        Move Up
         or
        Move Down
        . You can't move conditions from one group to another.
      7. Click
        OK
         to save the signature definition.
    5. Save the application.
      1. Click
        OK
         to save the custom application definition.
      2. Click
        Commit
        .
    6. Validate that traffic matches the custom application as expected.
      1. Select
        Policies
        Security
         and
        Add
         a Security rule to allow the new application.
      2. Run the application from a client system that is between the firewall and the application and then check the Traffic logs (
        Monitor
        Traffic
        ) to make sure that you see traffic matching the new application (and that it's being handled per your policy rule).

    Application Override Policy

    Change how your configuration classifies applications.
    Application Override policies bypass layer 7 processing and threat inspection and instead use less secure stateful layer 4 inspection. Application Override policies prevent layer 7 application identification and layer 7 threat inspection and prevention; do not use Application Override unless you must. Instead, create a custom application or create a custom service timeout so that you maintain visibility into, control, and inspect the application in regular layer 7 Security rules.
    Only use Application Override in the most highly trusted environments where you can apply the principle of least privilege strictly. Install endpoint protection on endpoints, install compensating protections on servers, and make the Application Override rule as restrictive as possible (only the necessary source, destination, users, applications, and services) since you have limited visibility into the traffic. If you must use Application Override and the traffic traverses multiple inspection points such as a data center and then a perimeter, apply Application Override consistently along the path.
    There are two main use cases for Application Override:
    • In
      Prisma Access
      , you can’t make application-level gateway (ALG) changes in the cloud and you can’t push them through Panorama, so if you need a SIP ALG, you may need to create an Application Override rule.
    • In environments where SMB traffic performance is critically low and Disable Server Response Inspection (DRSI) doesn’t improve performance enough, you may need to create an Application Override rule (Application Override rules are processed faster at the expense of security because they bypass layer 7 inspection).

    Cloud Managed

    Stateful layer 4 inspection for SIP-ALG and SMB traffic that overrides application-based policy.
    Palo Alto Networks determines what an application is irrespective of port, protocol, encryption, (SSH or SSL) or any other evasive tactic used by the application. Configure your won Application Override Policy to chance how traffic get classified to support internal or proprietary application.
    To change how your configuration classifies network traffic into applications, you can specify application override policies. For example, if you want to control one of your custom applications, an application override policy can be used to identify traffic for that application according to zone, source and destination address, and protocol. If you have network applications that are classified as “unknown,” you can create new application definitions for them
    Review your existing policy rulebase. If you have any Application Override rules for traffic other than SMB or SIP, convert the rule to an App-ID based rule so that you can decrypt and inspect the traffic at layer 7 and prevent threats.
    To create an application override:
    1. First go to
      Manage
      Configuration
      NGFW and Prisma Access
      Objects
      Applications
       and create a custom application. This is the application that you want traffic to match instead of the App-ID
      Prisma Access
       uses.
    2. Return to
      Manage
      Configuration
      NGFW and Prisma Access
      Network Policies
      Application Override
       to then create your application override security rule.
      This rule specifies when
      Prisma Access
       should invoke the custom application.
      Consider that when you create an application override security rule, you’re limiting
      Prisma Access
       App-ID from classifying traffic and performing threat inspection based on that application identification.
      To support internal proprietary applications, it’s worth thinking about creating a custom application (instead of an application override rule) that include the application signature so that
      Prisma Access
       performs layer 7 inspection and scans the application traffic for threats.

    PAN-OS & Panorama

    Stateful layer 4 inspection for SIP-ALG and SMB traffic that overrides application-based policy.
    Palo Alto Networks determines what an application is irrespective of port, protocol, encryption, (SSH or SSL) or any other evasive tactic used by the application. Configure your own Application Override Policy to chance how traffic get classified to support internal or proprietary application.
    To change how your configuration classifies network traffic into applications, you can specify application override policies. For example, if you want to control one of your custom applications, an application override policy can be used to identify traffic for that application according to zone, source and destination address, port, and protocol. If you have network applications that are classified as “unknown,” you can create new application definitions for them
    Review your existing policy rulebase. If you have any Application Override rules for traffic other than SMB or SIP, convert the rule to an App-ID based rule so that you can decrypt and inspect the traffic at layer 7 and prevent threats.
    To create an application override:
    1. Go to
      Objects
      Applications
      Add
       and create a custom application. This is the application that you want traffic to match instead of the App-ID your configuration uses.
    2. Go to
      Policies
      Application Override
       to then create your application override security rule.
      This rule specifies when
      Prisma Access
       should invoke the custom application.
      Consider that when you create an application override security rule, you’re limiting
      Prisma Access
       App-ID from classifying traffic and performing threat inspection based on that application identification.
      To support internal proprietary applications, it’s worth thinking about creating a custom application (instead of an application override rule) that include the application signature so that
      Prisma Access
       performs layer 7 inspection and scans the application traffic for threats.

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