MediumSplunk security content Michael Haag +1Threat hunting

Windows Defender ASR Rules Stacking

Description

The following analytic identifies security events from Microsoft Defender, focusing on Exploit Guard and Attack Surface Reduction (ASR) features. It detects Event IDs 1121, 1126, 1131, and 1133 for blocked operations, and Event IDs 1122, 1125, 1132, and 1134 for audit logs. Event ID 1129 indicates user overrides, while Event ID 5007 signals configuration changes. This detection uses a lookup to correlate ASR rule GUIDs with descriptive names. Monitoring these events is crucial for identifying unauthorized operations, potential security breaches, and policy enforcement issues. If confirmed malicious, attackers could bypass security measures, execute unauthorized actions, or alter system configurations.

Detection logic

Detection requirements

Platform: Containers ESXi IaaS Identity Provider Linux macOS Network Devices Office Suite SaaS Windows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
Log source category: windows_event_log_defender_1121 windows_event_log_defender_1122 windows_event_log_defender_1125 windows_event_log_defender_1126 windows_event_log_defender_1129 windows_event_log_defender_1131 windows_event_log_defender_1133 windows_event_log_defender_1134 windows_event_log_defender_5007

Known benign triggers

False positives are not expected with this analytic, since it is a hunting analytic. It is meant to show the use of ASR rules and how they can be used to detect malicious activity.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
asrgen.streamlit.app	Unclassified	5
learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/attack-surface-reduction?view=o365-worldwide	Product documentation	Only this detection cites it

Detection rules

Windows Defender ASR Rules Stacking

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules