To prevent malicious actors from abusing file-sharing applications for data exfiltration, App-ID provides a granular approach to managing application traffic. Palo Alto Networks' App-ID is a technology that identifies applications traversing the network, regardless of port, protocol, encryption (SSL), or evasive tactics. By leveraging App-ID, security engineers can implement policies that restrict the use of specific applications or functionalities based on job functions, ensuring that only authorized users or groups can use file-sharing applications while blocking unauthorized or malicious usage.

Here’s why the options are evaluated this way:

Option A: DNS Security focuses on identifying and blocking malicious domains. While it plays a critical role in preventing certain attacks (like command-and-control traffic), it is not effective for managing application usage. Hence, this is not the best approach.

Option B (Correct): App-ID provides the ability to identify file-sharing applications (such as Dropbox, Google Drive, or OneDrive) and enforce policies to restrict their use. For example, you can create a security rule allowing file-sharing apps only for specific job functions, such as HR or marketing, while denying them for other users. This targeted approach ensures legitimate business needs are not disrupted, which aligns with the requirement of not impacting valid users.

Option C: Blocking all file-sharing applications outright using DNS Security is a broad measure that will indiscriminately impact legitimate users. This does not meet the requirement of allowing specific users to continue using file-sharing applications.

Option D: While App-ID can block file-sharing applications outright, doing so will prevent legitimate usage and is not aligned with the requirement to allow usage based on job functions.

How to Implement the Solution (Using App-ID):

Identify the relevant file-sharing applications using App-ID in Palo Alto Networks’ predefined application database.

Create security policies that allow these applications only for users or groups defined in your directory (e.g., Active Directory).

Use custom App-ID filters or explicit rules to control specific functionalities of file-sharing applications, such as uploads or downloads.

Monitor traffic to ensure that only authorized users are accessing the applications and that no malicious activity is occurring.