A correlation object is a definition file that specifies patterns to match against, the data sources to use for the lookups, and time period within which to look for these patterns. A pattern is a boolean structure of conditions that queries the following data sources (or logs) on the firewall: application statistics, traffic, traffic summary, threat summary, threat, data filtering, and URL filtering. Each pattern has a severity rating, and a threshold for the number of times the pattern match must occur within a defined time limit to indicate malicious activity. When the match conditions are met, a correlated event is logged.
A correlation object can connect isolated network events and look for patterns that indicate a more significant event. These objects identify suspicious traffic patterns and network anomalies, including suspicious IP activity, known command-and-control activity, known vulnerability exploits, or botnet activity that, when correlated, indicate with a high probability that a host on the network has been compromised. Correlation objects are defined and developed by the Palo Alto Networks Threat Research team, and are delivered with the weekly dynamic updates to the firewall and Panorama. To obtain new correlation objects, the firewall must have a Threat Prevention license. Panorama requires a support license to get the updates.
The patterns defined in a correlation object can be static or dynamic. Correlated objects that include patterns observed in WildFire are dynamic, and can correlate malware patterns detected by WildFire with command-and-control activity initiated by a host that was targeted with the malware on your network. For example, when a host submits a file to the WildFire cloud and the verdict is malicious, the correlation object looks for other hosts or clients on the network that exhibit the same behavior seen in the cloud. If the malware sample had performed a DNS query and browsed to a malware domain, the correlation object will parse the logs for a similar event. When the activity on a host matches the analysis in the cloud, a high severity correlated event is logged.