Discovered Device Incorrectly Merged: Overlapping IP

Rule ID

PH_Rule_Avail_PH_23

Default Status

Enabled

Description

Detects that a discovered device is merged (incorrectly) to an existing CMDB device with different host name because of one or more overlapping IP addresses. To avoid such merging, include the overlapping IP addresses in the list of Virtual IP addresses and rediscover

Severity

MITRE ATT&CK® Tactics

FortiSIEM

MITRE ATT&CK® Techniques

No Technique Specified

Impacts

Internal

Data Source

FortiSIEM Self Monitoring

Detection

Correlation

Remediation Guidance

This is caused by two discovered devices sharing a common IP address. If this is a misconfiguration, then fix it, delete the devices and re-discover. If the devices need to share an address, then this address is likely a Virtual IP. Create an exception in Admin > Settings > Discovery > general > Virtual IP; then delete the devices and rediscover.

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.

Overlap

SubPattern Definitions

SubPattern Name: Overlap

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_AUDIT_DEVICE_MERGED_BY_IP_WITH_DIFF_NAME" AND phEventCategory = 2

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, targetHostName, overlapIp

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 = Overlap.hostName,
targetHostName = Overlap.targetHostName,
 overlapIp = Overlap.overlapIp

FortiSIEM Rules