Windows PowGoop Beacon Decoding

name: Windows PowGoop Beacon Decoding
id: 4d0480d8-80c4-4f74-84fe-2ab7fb514c85
version: 2
creation_date: '2026-05-05'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: |-
    Detects a DLL decoding and executing the PowGoop config.txt payload, the stage in the MuddyWater infection chain where an obfuscated PowerShell beacon is unwrapped and live C2 communication begins.
    PowGoop is the primary loader used by MuddyWater (also tracked as SeedWorm, Static Kitten, and MERCURY) and has been their main initial access loader since at least 2020.
    It abuses DLL side-loading against a fake GoogleUpdate.exe to execute a multi-stage decoding chain, a fully functional PowerShell backdoor disguised with a benign extension.
    The config.txt contains a hardcoded C2 address and victim GUID, beacons via modified base64-encoded HTTP, and runs C2 traffic under the legitimate Google Update process to evade network detection.
data_source:
    - Sysmon EventID 1
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime

    from datamodel=Endpoint.Processes where

    Processes.parent_process_path="*rundll32.exe"
    Processes.process_name="powershell.exe"
    Processes.process="*FromBase64String*"
    Processes.process="*config.txt*"

    by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
       Processes.parent_process_name Processes.parent_process_exec Processes.action
       Processes.dest Processes.process_current_directory Processes.process_path
       Processes.process_integrity_level Processes.original_file_name Processes.parent_process
       Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
       Processes.process_guid Processes.process_id Processes.user Processes.process_name

    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_powgoop_beacon_decoding_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: Some security tools or legitimate debugging processes may decode config files similar to PowGoop. Review and whitelist trusted applications to reduce false alerts.
references:
    - https://www.cisa.gov/uscert/sites/default/files/publications/AA22-055A_Iranian_Government-Sponsored_Actors_Conduct_Cyber_Operations.pdf
drilldown_searches:
    - earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
      name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | 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: Potential PowGoop Beacon Decoding activity observed on $dest$ via $process$.
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: parent_process_name
      type: parent_process_name
analytic_story:
    - Compromised Windows Host
asset_type: Endpoint
mitre_attack_id:
    - T1059.001
    - T1001
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/T1059.001/snapattack/snapattack.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit