| ID | Technique | Tactic |
|---|---|---|
| T1566.001 | Spearphishing Attachment | Initial Access |
| T1566.002 | Spearphishing Link | Initial Access |
| T1059 | Command and Scripting Interpreter | Execution |
Detection: 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.
Search
1`ms_defender` EventCode IN (1121, 1122, 1125, 1126, 1129, 1131, 1132, 1133, 1134, 5007)
2| stats count min(_time) as firstTime max(_time) as lastTime by host Parent_Commandline, Process_Name, Path, ID, EventCode
3| lookup asr_rules ID OUTPUT ASR_Rule
4| fillnull value=NULL
5| `security_content_ctime(firstTime)`
6| `security_content_ctime(lastTime)`
7| rename host as dest
8| `windows_defender_asr_rules_stacking_filter`
Data Source
| Name | Platform | Sourcetype | Source | Supported App |
|---|---|---|---|---|
| Windows Event Log Defender 1121 |  Windows |
'xmlwineventlog' |
'WinEventLog:Microsoft-Windows-Windows Defender/Operational' |
N/A |
Macros Used
| Name | Value |
|---|---|
| ms_defender | source="WinEventLog:Microsoft-Windows-Windows Defender/Operational" |
| windows_defender_asr_rules_stacking_filter | search * |
windows_defender_asr_rules_stacking_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
KillChainPhase.DELIVERY
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10
APT-C-36
APT1
APT12
APT19
APT28
APT29
APT30
APT32
APT33
APT37
APT38
APT39
APT41
Ajax Security Team
Andariel
BITTER
BRONZE BUTLER
BlackTech
Cobalt Group
Confucius
DarkHydrus
Darkhotel
Dragonfly
EXOTIC LILY
Elderwood
Ember Bear
FIN4
FIN6
FIN7
FIN8
Ferocious Kitten
Gallmaker
Gamaredon Group
Gorgon Group
Higaisa
Inception
IndigoZebra
Kimsuky
Lazarus Group
LazyScripter
Leviathan
Machete
Malteiro
Mofang
Molerats
MuddyWater
Mustang Panda
Naikon
Nomadic Octopus
OilRig
PLATINUM
Patchwork
RTM
Rancor
Sandworm Team
SideCopy
Sidewinder
Silence
TA2541
TA459
TA505
TA551
The White Company
Threat Group-3390
Tonto Team
Transparent Tribe
Tropic Trooper
WIRTE
Windshift
Wizard Spider
admin@338
menuPass
APT1
APT28
APT29
APT3
APT32
APT33
APT39
BlackTech
Cobalt Group
Confucius
EXOTIC LILY
Earth Lusca
Elderwood
Ember Bear
Evilnum
FIN4
FIN7
FIN8
Kimsuky
Lazarus Group
LazyScripter
Leviathan
LuminousMoth
Machete
Magic Hound
Mofang
Molerats
MuddyWater
Mustang Panda
Mustard Tempest
OilRig
Patchwork
Sandworm Team
Sidewinder
TA2541
TA505
Transparent Tribe
Turla
Windshift
Wizard Spider
ZIRCONIUM
APT19
APT32
APT37
APT39
Dragonfly
FIN5
FIN6
FIN7
Fox Kitten
Ke3chang
OilRig
Stealth Falcon
Whitefly
Windigo
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
| Setting | Value |
|---|---|
| Disabled | true |
| Cron Schedule | 0 * * * * |
| Earliest Time | -70m@m |
| Latest Time | -10m@m |
| Schedule Window | auto |
| Creates Risk Event | False |
This configuration file applies to all detections of type hunting.
Implementation
The following analytic requires collection of Windows Defender Operational logs in either XML or multi-line. To collect, setup a new input for the Windows Defender Operational logs. In addition, it does require a lookup that maps the ID to ASR Rule name. Note that Audit and block Event IDs have different fields, therefore the analytic will need to be modified for each type of event. The analytic can be modified to look for specific ASR rules, or to look for specific Event IDs. EventID 5007 is a change in the registry, and may be a false positive. This can be removed from the search if desired.
Known False Positives
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.
Associated Analytic Story
Risk Based Analytics (RBA)
| Risk Message | Risk Score | Impact | Confidence |
|---|---|---|---|
| An ASR rule, $ASR_Rule$, was triggered on $dest$. | 50 | 50 | 100 |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
References
Detection Testing
| Test Type | Status | Dataset | Source | Sourcetype |
|---|---|---|---|---|
| Validation | ✅ Passing | N/A | N/A | N/A |
| Unit | ✅ Passing | Dataset | WinEventLog:Microsoft-Windows-Windows Defender/Operational |
xmlwineventlog |
| Integration | ✅ Passing | Dataset | WinEventLog:Microsoft-Windows-Windows Defender/Operational |
xmlwineventlog |
Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 3