Detection: Windows Wermgr Alternate Data Stream in Temp Dir

Updated Date: 2026-06-11 ID: 65222e9b-9d0b-4bfe-8da1-199b98e1d44a Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the wermgr.exe process creating an alternate stream in the temp directory. It leverages Sysmon EventID 15 to identify these actions. This activity is significant because wermgr.exe is typically associated with error reporting, not file creation. Such activity is significant as it may indicate RoguePlanet malware, which creates an alternate stream in the temp directory to execute malicious code. If confirmed malicious, this could lead to further malware infections, data exfiltration, or system compromise.

Search

 1`sysmon`
 2EventCode=15
 3TargetFilename = "*\\Temp\\*"
 4TargetFilename = "*\\wermgr.exe:*"
 5
 6
 7| stats count min(_time) as firstTime
 8              max(_time) as lastTime
 9by dest dvc file_hash file_name file_path process_exec
10   process_guid process_id process_name process_path
11   signature signature_id user_id vendor_product Contents Image
12
13
14| `security_content_ctime(firstTime)`
15
16| `security_content_ctime(lastTime)`
17
18| `windows_wermgr_alternate_data_stream_in_temp_dir_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 15	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`

Macros Used

Name	Value
sysmon	`(source=WinEventLog:Microsoft-Windows-Sysmon/Operational OR source=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational OR source=Syslog:Linux-Sysmon/Operational)`
windows_wermgr_alternate_data_stream_in_temp_dir_filter	`search *`

windows_wermgr_alternate_data_stream_in_temp_dir_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
T1564.004	NTFS File Attributes	Stealth

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 Finding (Notable)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances of wermgr.exe may be used.

Known False Positives

No false positives have been identified at this time.

Associated Analytic Story

RoguePlanet

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
A [$process_name$] created a wermgr.exe alternate stream in the temp directory on $dest$ by $user$	dest	system	20

References

https://github.com/MSNightmare/RoguePlanet/tree/main

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: 1