FortiSIEM Rules

Server Network Low Port Staying Down

Rule ID

PH_Rule_Avail_25

Default Status

Enabled

Description

Detects a low TCP/UDP port on a server staying down - that is, went from up to down and did not come up in 10 min

Severity

7

Category

Availability

MITRE ATT&CK® Tactics

Network

MITRE ATT&CK® Techniques

No Technique Specified

Impacts

Server

Data Source

Windows Performance Monitoring via OMI or FortiSIEM Agent, Linux via SNMP

Detection

Correlation

Remediation Guidance

Identify the root cause and solve the issue

Time Window

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

600 seconds

Trigger Conditions

If the following defined pattern/s occur within a 600 second time window.

PortDown NOT_FOLLOWED_BY PortStillDown

Global Constraint

This defines how two or more distinct events are related in a time-series based action. e.g. An event occurs followed by another event if the source IP, user, and messageId are the same

PortStillDown.hostName = PortDown.hostName AND PortStillDown.hostIpAddr = PortDown.hostIpAddr AND PortStillDown.serviceName = PortDown.serviceName AND PortStillDown.ipPort = PortDown.ipPort AND PortStillDown.ipProto = PortDown.ipProto

SubPattern Definitions

SubPattern Name: PortDown

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

eventType = "PH_DEV_MON_PORT_CLOSE" AND ipPort <= 1024 AND hostIpAddr IN (Group@PH_SYS_DEVICE_Server)

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

hostName,hostIpAddr,serviceName,ipProto,ipPort

Aggregate Constraint

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

COUNT(*) >= 1
Operator Rank: 0 Operator Type: NOT_FOLLOWED_BY

This operator defines the logic condition relating to the prior event subpattern clause and the following event subpattern clause

SubPattern Name: PortStillDown

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

eventType = "PH_DEV_MON_PORT_OPEN" AND ipPort <= 1024 AND hostIpAddr IN (Group@PH_SYS_DEVICE_Server)

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

hostName,hostIpAddr,serviceName,ipProto,ipPort

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

 hostName=PortDown.hostName,
hostIpAddr=PortDown.hostIpAddr,
serviceName=PortDown.serviceName,
ipPort=PortDown.ipPort,
ipProto=PortDown.ipProto