WildFire Best Practices

Follow the best practices to secure your network from Layer 4 and Layer 7 evasions to ensure reliable content identification and analysis. Specifically, make sure to implement the best practices for TCP settings (

Device

Setup

Session

TCP Settings

) and Content-ID™ settings (

Device

Setup

Content-ID

Content-ID Settings

).

Make sure that you also have an active Threat Prevention subscription. Together, WildFire® and Threat Prevention enable comprehensive threat detection and prevention.

Download and install content updates on a daily basis to receive the latest product updates and threat protections generated by Palo Alto Networks. Refer to Install Content and Software Updates for more information about what is included in the update packages.

If the firewall is configured to decrypt SSL traffic, enable the firewall to

Forward Decrypted SSL Traffic for WildFire Analysis

(PAN-OS 8.1, PAN-OS 9.0, PAN-OS 9.1). Only a superuser can enable this option.

Use the default WildFire Analysis profile to define the traffic that the firewall should forward for WildFire analysis (

Objects

Security Profiles

WildFire Analysis

). The default WildFire Analysis profile ensures complete WildFire coverage for all traffic that your Security policy allows—it specifies that all supported file types across all applications are forwarded for WildFire analysis regardless whether the files are uploaded or downloaded.

If you choose to create a custom WildFire Analysis profile, it is a best practice to still set the profile to forward

any

file type. This enables the firewall to automatically begin forwarding file types as they become supported for WildFire analysis.

For details on applying a WildFire Analysis profile to firewall traffic, review how to

Forward Files for WildFire Analysis

(PAN-OS 8.1, PAN-OS 9.0, PAN-OS 9.1).

WildFire Action settings in the Antivirus profile may impact traffic if the traffic generates a WildFire signature that results in a reset or a drop action. You can exclude internal traffic, such as software distribution applications through which you deploy custom-built programs, to transition safely to best practices because WildFire may identify custom-built programs as malicious and generate a signature for them. Check

Monitor

Logs

WildFire Submissions

to see if any internal custom-built programs trigger WildFire signatures.

While you are configuring the firewall to forward files for WildFire analysis (PAN-OS 8.1, PAN-OS 9.0, PAN-OS 9.1), review the file

Size Limit

for all supported file types. Set the

Size Limit

for all file types to the default limits. (Select

Device

Setup

WildFire

and edit the General Settings to adjust file size limits based on file type. You can view the Help information to find the default size limit for each file type).

About the Default File Size Limits for WildFire Forwarding

The default file size limits on the firewall are designed to include the large majority of malware in the wild (which is smaller than the default size limits) and to exclude large files that are very unlikely to be malicious and can impact WildFire file-forwarding capacity. Because the firewall has a specific capacity reserved to forward files for WildFire analysis, forwarding high numbers of large files might cause the firewall to skip forwarding some files. This condition can occur when the maximum file size limits are configured for a file type that is traversing the firewall at a high rate. In this case, a potentially malicious file might not be forwarded for WildFire analysis. Consider this possible condition if you would like to increase the size limit for files other than PEs beyond their default size limit.

The following graph is a representative illustration of the distribution of file sizes for malware as observed by the Palo Alto Networks threat research team. The firewall default file size settings can be increased to the maximum file size setting to gain a relatively small increase in the malware catch rate for each file type.



If you are concerned specifically about uncommonly large malicious files, then you can increase file size limits beyond the default settings. In these cases, the following settings are recommended to catch rare, very large malicious files.

Select

Device

Setup

WildFire

and edit General Settings to adjust the

Size Limit

for each file type:

File Type	PAN-OS 9.0/9.1 File-Forwarding Maximum Size Recommendations	PAN-OS 8.1 File-Forwarding Maximum Size Recommendations	PAN-OS 8.0 File-Forwarding Maximum Size Recommendations
pe	16MB	10MB	10MB
apk	10MB	10MB	10MB
pdf	3,072KB	500KB	500KB
ms-office	16,384KB	500KB	500KB
jar	5MB	5MB	5MB
flash	5MB	5MB	5MB
MacOSX	10MB	1MB	1MB
archive	50MB	10MB	10MB
linux	50MB	10MB	10MB
script	20KB	20KB	—