Suspicious mshta spawn

SPLUNK detection rule by Michael Haag, Splunk · Apache-2.0

The following analytic detects the spawning of mshta.exe by wmiprvse.exe or svchost.exe. This behavior is identified using Endpoint Detection and Response (EDR) data, focusing on process creation events where the parent process is either wmiprvse.exe or svchost.exe. This activity is significant as it may indicate the use of a DCOM object to execute malicious scripts via mshta.exe, a common tactic in sophisticated attacks. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to system compromise and further malicious activities.

name: Suspicious mshta spawn
id: 4d33a488-5b5f-11eb-ae93-0242ac130002
version: 13
creation_date: '2021-01-20'
modification_date: '2026-05-13'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic detects the spawning of mshta.exe by wmiprvse.exe or svchost.exe. This behavior is identified using Endpoint Detection and Response (EDR) data, focusing on process creation events where the parent process is either wmiprvse.exe or svchost.exe. This activity is significant as it may indicate the use of a DCOM object to execute malicious scripts via mshta.exe, a common tactic in sophisticated attacks. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to system compromise and further malicious activities.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count values(Processes.process_name) as process_name values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE (
            Processes.parent_process_name=svchost.exe
            OR
            Processes.parent_process_name=wmiprvse.exe
        )
        AND `process_mshta`
      BY Processes.action Processes.dest Processes.original_file_name
         Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
         Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
         Processes.process Processes.process_exec Processes.process_guid
         Processes.process_hash Processes.process_id Processes.process_integrity_level
         Processes.process_name Processes.process_path Processes.user
         Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `suspicious_mshta_spawn_filter`
how_to_implement: 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: Although unlikely, some legitimate applications may exhibit this behavior, triggering a false positive.
references:
    - https://codewhitesec.blogspot.com/2018/07/lethalhta.html
    - https://github.com/redcanaryco/AtomicTestHarnesses
    - https://redcanary.com/blog/introducing-atomictestharnesses/
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: mshta.exe spawned by wmiprvse.exe on $dest$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Suspicious MSHTA Activity
    - Living Off The Land
    - APT37 Rustonotto and FadeStealer
asset_type: Endpoint
mitre_attack_id:
    - T1218.005
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.005/atomic_red_team/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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