Suspicious microsoft workflow compiler usage

name: Suspicious microsoft workflow compiler usage
id: 9bbc62e8-55d8-11eb-ae93-0242ac130002
version: 10
date: '2026-03-10'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic identifies the usage of microsoft.workflow.compiler.exe, a rarely utilized executable typically found in C:\Windows\Microsoft.NET\Framework64\v4.0.30319. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution telemetry. The significance of this activity lies in its uncommon usage, which may indicate malicious intent such as code execution or persistence mechanisms. If confirmed malicious, an attacker could leverage this process to execute arbitrary code, potentially leading to unauthorized access or further compromise of the system.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE (
            Processes.process_name=microsoft.workflow.compiler.exe
            OR
            Processes.original_file_name=Microsoft.Workflow.Compiler.exe
        )
      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_microsoft_workflow_compiler_usage_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, limited instances have been identified coming from native Microsoft utilities similar to SCCM.
references:
    - https://lolbas-project.github.io/lolbas/Binaries/Msbuild/
    - https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218/T1218.md#atomic-test-6---microsoftworkflowcompilerexe-payload-execution
drilldown_searches:
    - name: View the detection results for - "$dest$" and "$user$"
      search: '%original_detection_search% | search  dest = "$dest$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") starthoursago=168  | 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: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: Suspicious microsoft.workflow.compiler.exe process ran on $dest$ by $user$
    risk_objects:
        - field: dest
          type: system
          score: 50
        - field: user
          type: user
          score: 50
    threat_objects: []
tags:
    analytic_story:
        - Trusted Developer Utilities Proxy Execution
        - Living Off The Land
    asset_type: Endpoint
    mitre_attack_id:
        - T1127
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1127/atomic_red_team/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog