Windows: Disabling Windows Event Auditing

Rule ID

PH_Rule_SIGMA_245

Default Status

Enabled

Description

Detects scenarios where system auditing (ie: windows event log auditing) is disabled. This may be used in a scenario where an entity would want to bypass local logging to evade detection when windows event logging is enabled and reviewed. Also, it is recommended to turn off "Local Group Policy Object Processing" via GPO, which will make sure that Active Directory GPOs take precedence over local/edited computer policies via something such as "gpedit.msc". Please note, that disabling "Local Group Policy Object Processing" may cause an issue in scenarios of one off specific GPO modifications -- however it is recommended to perform these modifications in Active Directory anyways. . This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_disable_event_logging.yml

Severity

MITRE ATT&CK® Tactics

Defense Evasion

Defense Evasion consists of techniques that adversaries use to avoid detection throughout their compromise. Techniques used for defense evasion include uninstalling/disabling security software or obfuscating/encrypting data and scripts. Adversaries also leverage and abuse trusted processes to hide and masquerade their malware. Other tactics’ techniques are cross-listed here when those techniques include the added benefit of subverting defenses.

https://attack.mitre.org/tactics/TA0005

MITRE ATT&CK® Techniques

T1562.002

Impair Defenses: Disable Windows Event Logging

Adversaries may disable Windows event logging to limit data that can be leveraged for detections and audits.

https://attack.mitre.org/techniques/T1562/002

Impacts

Server

Data Source

Windows Security Log via OMI or 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.

Filter

SubPattern Definitions

SubPattern Name: Filter

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="Win-Security-4719" AND actionName REGEXP ".*%%8448.*|.*%%8450.*"

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

actionName,hostName

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

actionName = Filter.actionName,
hostName = Filter.hostName

FortiSIEM Rules