Rundll32 Control RunDLL World Writable Directory
Description
The following analytic detects the execution of rundll32.exe with the Control_RunDLL
command, loading files from world-writable directories such as windows\temp, programdata, or appdata. This detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process command-line data and specific directory paths. This activity is significant as it may indicate an attempt to exploit CVE-2021-40444 or similar vulnerabilities, allowing attackers to execute arbitrary code. If confirmed malicious, this could lead to unauthorized code execution, privilege escalation, or persistent access within the environment.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2024-05-28
- Author: Michael Haag, Splunk
- ID: 1adffe86-10c3-11ec-8ce6-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_rundll32` Processes.process=*Control_RunDLL* AND Processes.process IN ("*\\appdata\\*", "*\\windows\\temp\\*", "*\\programdata\\*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `rundll32_control_rundll_world_writable_directory_filter`
Macros
The SPL above uses the following Macros:
rundll32_control_rundll_world_writable_directory_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- Processes.dest
- Processes.user
- Processes.parent_process_name
- Processes.parent_process
- Processes.original_file_name
- Processes.process_name
- Processes.process
- Processes.process_id
- Processes.parent_process_path
- Processes.process_path
- Processes.parent_process_id
How To Implement
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
This may be tuned, or a new one related, by adding .cpl to command-line. However, it's important to look for both. Tune/filter as needed.
Associated Analytic Story
- Suspicious Rundll32 Activity
- Microsoft MSHTML Remote Code Execution CVE-2021-40444
- Living Off The Land
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
80.0 | 80 | 100 | An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to load a suspicious file from disk. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- https://strontic.github.io/xcyclopedia/library/rundll32.exe-111474C61232202B5B588D2B512CBB25.html
- https://app.any.run/tasks/36c14029-9df8-439c-bba0-45f2643b0c70/
- https://attack.mitre.org/techniques/T1218/011/
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.002/T1218.002.yaml
- https://redcanary.com/blog/intelligence-insights-december-2021/
Test Dataset
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 | version: 2