An administrator is required to create an application-based Security policy rule to allow Evernote. The Evernote application implicitly uses SSL and…

The Palo Alto Networks firewall's App-ID engine automatically identifies application dependencies. When you create a Security policy rule to allow a specific application, such as Evernote, the firewall implicitly allows the applications on which Evernote depends (e.g., SSL, web-browsing) for that session. This ensures that only the traffic required for the Evernote application is permitted, adhering to the principle of least privilege. Adding only the 'evernote' application is the most precise and secure method, representing the minimum required configuration.

A: Creating a second, broader rule for HTTP and SSL is unnecessary and overly permissive, as it would allow all HTTP/SSL traffic, not just traffic related to Evernote.

B: An Application Override bypasses App-ID inspection and is used for custom or unknown applications, not for well-defined applications like Evernote. This is an insecure practice.

C: Adding SSL and HTTP to the same rule is not the minimum requirement. This would explicitly allow all SSL and HTTP traffic, defeating the purpose of application-specific control.

1. Palo Alto Networks PAN-OS® Administrator’s Guide 10.2: In the section "Security Policy

" it explains how App-ID works. "When you create a Security policy rule that allows a specific application

you do not also have to create a rule that allows the applications on which the allowed application depends. The firewall automatically allows the dependent applications for you." This concept is detailed under "Create a Security Policy Rule."

2. Palo Alto Networks PAN-OS® Administrator’s Guide 10.2: The section on "Application Dependencies" further clarifies this behavior. "For example

to allow facebook-base

you do not need to add web-browsing and ssl to the rule because they are dependencies of facebook-base and are implicitly allowed." The same principle applies to Evernote and its dependencies.

3. Palo Alto Networks App-ID™ Technology Overview: This document describes the core functionality of App-ID

stating

"App-ID understands that some applications rely on other applications to function. For example

Facebook applications depend on facebook-base

which in turn depends on web-browsing and SSL. App-ID automatically identifies and allows these dependencies."