Detection: Suspicious DLLHost no Command Line Arguments

Updated Date: 2026-05-13 ID: ff61e98c-0337-4593-a78f-72a676c56f26 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects instances of DLLHost.exe executing without command line arguments. This behavior is unusual and often associated with malicious activities, such as those performed by Cobalt Strike. The detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs. This activity is significant because DLLHost.exe typically requires arguments to function correctly, and its absence may indicate an attempt to evade detection. If confirmed malicious, this could lead to unauthorized actions like credential dumping or file manipulation, posing a severe threat to the environment.

Search

 1
 2| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where
 3(Processes.process_name=dllhost.exe OR Processes.original_file_name=dllhost.exe)
 4Processes.process IN ("*dllhost","*dllhost.exe", "*dllhost.exe\"")
 5by Processes.action Processes.dest Processes.original_file_name
 6   Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
 7   Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
 8   Processes.process Processes.process_exec Processes.process_guid Processes.process_hash
 9   Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path
10   Processes.user Processes.user_id Processes.vendor_product 
11| `drop_dm_object_name(Processes)`
12
13| `security_content_ctime(firstTime)`
14
15| `security_content_ctime(lastTime)`
16
17| `suspicious_dllhost_no_command_line_arguments_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	`'crowdstrike:events:sensor'`	`'crowdstrike'`
Sysmon EventID 1	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Windows Event Log Security 4688	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Security'`

Macros Used

Name	Value
security_content_summariesonly	`summariesonly=`summariesonly_config `allow_old_summaries=`oldsummaries_config `fillnull_value=`fillnull_config``
suspicious_dllhost_no_command_line_arguments_filter	`search *`

suspicious_dllhost_no_command_line_arguments_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
T1055	Process Injection	Privilege Escalation

Exploitation

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 Finding (Notable)	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Intermediate Finding (Risk Event)	Yes

TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

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 may be present in small environments. Tuning may be required based on parent process.

Associated Analytic Story

Finding

Title	Entity Field	Entity Type	Risk Score
Suspicious dllhost.exe process with no command line arguments executed on $dest$ by $user$	user	user	50

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
Suspicious dllhost.exe process with no command line arguments executed on $dest$ by $user$	dest	system	50

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/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: 14