Detection: Windows DotNet Binary in Non Standard Path

Updated Date: 2026-01-19 ID: fddf3b56-7933-11ec-98a6-acde48001122 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the execution of native .NET binaries from non-standard directories within the Windows operating system. It leverages Endpoint Detection and Response (EDR) telemetry, comparing process names and original file names against a predefined lookup "is_net_windows_file". This activity is significant because adversaries may move .NET binaries to unconventional paths to evade detection and execute malicious code. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, escalate privileges, or maintain persistence within the environment, posing a significant security risk. Also this analytic leverages a sub-search to enhance performance. sub-searches have limitations on the amount of data they can return. Keep this in mind if you have an extensive list of ransomware note file names.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
 3as lastTime
 4FROM datamodel=Endpoint.Processes where
 5NOT Processes.process_path IN (
 6      "*:\\Windows\\ADWS\\*",
 7      "*:\\Windows\\Microsoft.NET\\*",
 8      "*:\\Windows\\NetworkController\\*",
 9      "*:\\Windows\\System32\\*",
10      "*:\\Windows\\SystemApps\\*",
11      "*:\\Windows\\SysWOW64\\*",
12      "*:\\Windows\\WinSxS\\*"
13    )
14(
15  [ 
16| inputlookup is_net_windows_file
17    
18| search netFile=true
19    
20| fields originalFileName
21    
22| rename originalFileName as Processes.original_file_name
23    
24| format
25  ]
26)
27by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
28   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
29   Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
30   Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
31   Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
32
33| `drop_dm_object_name("Processes")`
34
35| `security_content_ctime(firstTime)`
36
37| `security_content_ctime(lastTime)`
38
39| lookup update=true is_net_windows_file filename as process_name OUTPUT netFile
40
41| lookup update=true is_net_windows_file originalFileName as original_file_name OUTPUT netFile
42
43| search netFile=true
44
45| `windows_dotnet_binary_in_non_standard_path_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_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_dotnet_binary_in_non_standard_path_filter	`search *`

windows_dotnet_binary_in_non_standard_path_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
T1036.003	Rename Legitimate Utilities	Defense Evasion
T1218.004	InstallUtil	Defense Evasion

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 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

False positives may be present and filtering may be required. Certain utilities will run from non-standard paths based on the third-party application in use.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

An instance of $parent_process_name$ spawning $process_name$ from a non-standard path was identified on endpoint $dest$ by user $user$.

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	49	process_name, parent_process_name
user	user	49	process_name, parent_process_name

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: 11