Detection: Windows GrimResource - MMC Process Accessing APDS DLL

Updated Date: 2026-04-13 ID: 872d1651-7838-4b47-ad3e-ef5e63453a7f Author: Raven Tait, Splunk Type: TTP Product: Splunk Enterprise Security

Description

GrimResource is a code execution technique discovered by Elastic Security in 2024 that abuses a stored XSS vulnerability in apds.dll to achieve arbitrary code execution inside mmc.exe, a signed, trusted Windows binary. The attack is delivered via a malicious .msc file (MMC Saved Console file). When the victim opens the .msc file, MMC processes an embedded transformNode operation that triggers the XSS in apds.dll, which is then leveraged to execute attacker-controlled script within the MMC process context.

Search

 1`wineventlog_security`
 2AccessList="%%4416"
 3EventID="4663"
 4ObjectName="*:\\Windows\\System32\\apds.dll"
 5ProcessName="*:\\Windows\\System32\\mmc.exe"
 6
 7| fillnull
 8
 9| stats count min(_time) as firstTime
10              max(_time) as lastTime
11  by Computer AccessList EventID ObjectName ProcessName
12
13
14| rename Computer as dest
15
16| `security_content_ctime(firstTime)`
17
18| `security_content_ctime(lastTime)`
19
20| `windows_grimresource___mmc_process_accessing_apds_dll_filter`

Data Source

Name	Platform	Sourcetype	Source
Windows Event Log Security 4663	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Security'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_grimresource___mmc_process_accessing_apds_dll_filter	`search *`

windows_grimresource___mmc_process_accessing_apds_dll_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

ID	Technique	Tactic
T1059.007	JavaScript	Execution
T1218.014	MMC	Stealth

Exploitation

Installation

DE.CM

CIS 10

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 Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Legitimate use of mmc.exe accessing apds.dll may occur during routine system management or troubleshooting. Verify with approved administrative activities to reduce false alerts.

Associated Analytic Story

Compromised Windows Host

Risk Based Analytics (RBA)

Risk Message:

mmc.exe accessed apds.dll on $dest$, consistent with GrimResource activity.

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	50	ObjectName

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Security`	`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: 1