FortiSIEM Rules

FortiSIEM: Too Many Unknown Events

Rule ID

PH_RULE_ERROR_TooManyUnknownEvents

Default Status

Enabled

Description

FortiSIEM is receiving too many unknown events, this may cause high CPU or delay.

Severity

9

Category

Performance

MITRE ATT&CK® Tactics

FortiSIEM

MITRE ATT&CK® Techniques

No Technique Specified

Impacts

System

Data Source

FortiSIEM Self Monitoring

Detection

Correlation

Remediation Guidance

To reduce CPU, try writing a basic log parser to capture the specified events. Alternatively, you can disable sending from the source device, or create a firewall drop rule to the FortiSIEM collector. If logs for a supported log type are coming in as unknown, please use the analytics tab, export to CSV format, and send to FortiSIEM support.

Time Window

If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.

300 seconds

Trigger Conditions

If the following defined pattern/s occur within a 300 second time window.

unknown_evts

SubPattern Definitions

SubPattern Name: unknown_evts

This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.

SubPattern Query

This is the query logic that matches incoming events

phEventCategory = 3  AND  eventType = "PH_PARSER_TOO_MANY_UNKNOWN_EVENTS"

Group by Attributes

This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID

relayDevIpAddr

Aggregate Constraint

This is most typically a numerical constraint that defines when the rule should trigger an incident

COUNT(*) >= 1

Incident Attribute Mapping

This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.

The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern

 srcIpAddr=unknown_evts.relayDevIpAddr