Detection: Suspicious Copy on System32

Updated Date: 2025-06-17 ID: ce633e56-25b2-11ec-9e76-acde48001122 Author: Teoderick Contreras, Nasreddine Bencherchali, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects potentially suspicious file copy operations targeting the System32 or SysWow64 directories as source, often indicative of malicious activity. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on activity initiated by command-line tools like cmd.exe or PowerShell. This behavior is significant as it may indicate an attempt to evade defenses by copying an existing binary from the system directory and renaming it. If confirmed malicious, this activity could allow an attacker to execute code undetected and potentially leading to system compromise or further lateral movement within the network.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
 3as lastTime from datamodel=Endpoint.Processes where
 4Processes.parent_process_name IN (
 5  "cmd.exe", 
 6  "powershell_ise.exe",
 7  "powershell.exe", 
 8  "pwsh.exe", 
 9  "sqlps.exe", 
10  "sqltoolsps.exe"
11)
12`process_copy` 
13Processes.process IN (
14  "* \"C:\\Windows\\System32\\*", 
15  "* \'C:\\Windows\\System32\\*", 
16  "* C:\\Windows\\System32\\*", 
17  "* \"C:\\Windows\\SysWow64\\*",
18  "* \'C:\\Windows\\SysWow64\\*",
19  "* C:\\Windows\\SysWow64\\*"
20)
21by Processes.action Processes.dest Processes.original_file_name
22Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
23Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
24Processes.process Processes.process_exec Processes.process_guid Processes.process_hash
25Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path
26Processes.user Processes.user_id Processes.vendor_product 
27
28| `drop_dm_object_name(Processes)`
29
30| `security_content_ctime(firstTime)` 
31
32| `security_content_ctime(lastTime)` 
33
34| `suspicious_copy_on_system32_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	`'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
process_copy	`(Processes.process_name=copy.exe OR Processes.original_file_name=copy.exe OR Processes.process_name=xcopy.exe OR Processes.original_file_name=xcopy.exe)`
suspicious_copy_on_system32_filter	`search *`

suspicious_copy_on_system32_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

Exploitation

DE.AE

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 Risk Event	True

This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

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

Copying files from System directories can happen for multiple admin reasons, allbeit rare without approval. Apply additional filters where needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Execution of copy exe to copy file from $process$ on $dest$

Risk Object	Risk Object Type	Risk Score	Threat Objects
dest	system	63	No Threat Objects
user	user	63	No Threat Objects

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