End-of-Life (EoL)
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. The WildFire cloud generates and distributes new WildFire signatures every five minutes, but you can configure the firewall to download signature updates every minute to ensure that you get the latest version within a minute of availability. If the firewall is configured to decrypt SSL traffic, enable the firewall to Forward Decrypted SSL Traffic for WildFire Analysis. Only a superuser can enable this option. Use the default WildFire Analysis profile to define the traffic the firewall should forward for WildFire analysis ( Objects > Security Profiles > WildFire Analysis). The default WildFire Analysis profile ensures complete WildFire coverage for all traffic your security policy allows—it specifies that all supported file types across all applications are forwarded for WildFire analysis, regardless of 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 allows 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.
While you are configuring the firewall to forward files for WildFire analysis, review the file Size Limit for all supported file types. Set the Size Limit for portable executables (PEs) to the maximum supported file size limit: 10 MB. Leave the Size Limit for all other file types set to the default limit. (Select Device > Setup > WildFire and edit the General Settings to adjust file size limits based on file type. Click the Help icon 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 exclude large files that are very unlikely to be malicious and can impact WildFire 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 might 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 the 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 sizes 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.
Recommended File Size Limits to Catch Uncommonly Large Malicious Files
If you are specifically concerned about uncommonly large malicious files might want to 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:
pe —10 MB apk—30 MB pdf—1,000 KB ms-office—2,000 KB jar—5 MB flash—5 MB MacOSX—1 MB archive—10 MB

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