Detection: Windows InstallUtil Remote Network Connection

Description

The following analytic detects the Windows InstallUtil.exe binary making a remote network connection. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and network telemetry. This activity is significant because InstallUtil.exe can be exploited to download and execute malicious code, bypassing application control mechanisms. If confirmed malicious, an attacker could achieve code execution, potentially leading to further system compromise, data exfiltration, or lateral movement within the network. Analysts should review the parent process, network connections, and any associated file modifications to determine the legitimacy of this activity.

Search

 1
 2| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
 3  where `process_installutil` by _time span=1h Processes.action Processes.dest Processes.original_file_name
 4  Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
 5  Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
 6  Processes.process Processes.process_exec Processes.process_guid Processes.process_hash
 7  Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path
 8  Processes.user Processes.user_id Processes.vendor_product 
 9
10| `drop_dm_object_name(Processes)` 
11
12| `security_content_ctime(firstTime)` 
13
14| `security_content_ctime(lastTime)` 
15
16| join process_id dest
17    [
18| tstats `security_content_summariesonly`
19        count FROM datamodel=Network_Traffic.All_Traffic where All_Traffic.dest_port !=
20        0 by All_Traffic.action All_Traffic.app All_Traffic.bytes All_Traffic.bytes_in All_Traffic.bytes_out
21        All_Traffic.dest  All_Traffic.dest_ip All_Traffic.dest_port All_Traffic.dvc All_Traffic.protocol
22        All_Traffic.protocol_version All_Traffic.src All_Traffic.src_ip All_Traffic.src_port
23        All_Traffic.transport All_Traffic.user All_Traffic.vendor_product All_Traffic.direction All_Traffic.process_id
24    
25| `drop_dm_object_name(All_Traffic)` 
26    
27| rename dest as command_and_control
28    
29| rename src as dest] 
30
31| table _time user src dest parent_process_name process_name process_path process process_id dest_port command_and_control
32
33| stats count min(_time) as firstTime max(_time) as lastTime values(process) as process values(command_and_control) as command_and_control by user dest process_name process_id dest_port parent_process_name 
34
35| `security_content_ctime(firstTime)` 
36
37| `security_content_ctime(lastTime)`
38| `windows_installutil_remote_network_connection_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 3	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

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

Limited false positives should be present as InstallUtil is not typically used to download remote files. Filter as needed based on Developers requirements.

Associated Analytic Story

• Compromised Windows Host

• Living Off The Land

• Signed Binary Proxy Execution InstallUtil

Risk Based Analytics (RBA)

Risk Message:

An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ generating a remote download.

References

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.004/T1218.004.md

Detection Testing

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: 13