Attackers often use Brotli compression to bypass traditional security mechanisms. To
close this visibility gap and improve security, the Content-Based Threat Detection
(CTD) engine, used by Palo Alto Networks NGFWs, now supports Brotli decompression
for improved analysis and threat detection of HTTP content. Brotli is a
high-efficiency data compression format that Google developed for HTTP web
applications and content. Palo Alto Networks Security subscription services, such as
Advanced Threat Prevention, Advanced WildFire, and Advanced URL Filtering, rely on
the CTD engine to facilitate traffic inspection. With the addition of the Brotli
decoder, the CTD engine now processes traffic that it previously dropped or passed
through the network as an unsupported content-encoding type, making the traffic
available for inspection by various Palo Alto Networks content inspection features.
This includes, but is not limited to, Precision AIĀ® optimized features such as
Advanced WildFire: Inline Cloud Analysis,
Advanced Threat Prevention: Inline Cloud
Analysis, and
Inline Deep Learning Analysis for Advanced URL
Filtering. This also applies to any HTTP traffic payloads that a
configured and enabled security policy processes. This new capability allows for
broader visibility into traffic. When you enable the feature, the existing content
decoder framework integrates this software-based Brotli library.