Self-signed Windows Certificate Added

Rule ID

PH_RULE_Cert_Mon_SelfSigned_Win_CertAdded

Default Status

Disabled

Description

Detects a self-signed certificate being added to a Windows host. Certificates that are signed by Certificate Authorities are excluded from this rule.

Severity

MITRE ATT&CK® Tactics

MITRE ATT&CK® Techniques

No Technique Specified

Impacts

Server

Data Source

Windows Certificate Monitoring via FortiSIEM Agent

Detection

Correlation

Remediation Guidance

No remediation guidance specified

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.

CertAdded

SubPattern Definitions

SubPattern Name: CertAdded

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 = "AO-WUA-Certificate-Added" AND isSelfSigned = 1 AND isCertAuthority = 0

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,certInfo,issuedTo,issuer

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 = CertAdded.hostName,
 certInfo = CertAdded.certInfo,
 issuedTo = CertAdded.issuedTo,
 issuer = CertAdded.issuer

FortiSIEM Rules