Windows EDRSilencer Execution

SPLUNK detection rule by Raven Tait, Splunk · Apache-2.0

Detects the usage of EDRSilencer. Inspired by the closed-source FireBlock tool from MdSec NightHawk, this custom tool was developed to block outbound traffic of running Endpoint Detection and Response (EDR) processes using Windows Filtering Platform (WFP) APIs. Its features include searching for running EDR processes and applying WFP filters to block outbound traffic, adding filters for specific processes, and removing filters either individually or globally. The tool includes a custom implementation to avoid file handle access issues with EDR processes by bypassing the CreateFileW API. It supports a wide range of EDRs, including Microsoft Defender, Carbon Black, SentinelOne, and more, though further testing on various EDRs is recommended. The tool has been tested on Windows 10 and Windows Server 2016, and its usage involves simple commands for blocking or unblocking traffic.

name: Windows EDRSilencer Execution
id: a206324d-4945-4b0c-a731-87c311ddae2f
version: 3
creation_date: '2026-05-05'
modification_date: '2026-06-13'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: |-
    Detects the usage of EDRSilencer.
    Inspired by the closed-source FireBlock tool from MdSec NightHawk, this custom tool was developed to block outbound traffic of running Endpoint Detection and Response (EDR) processes using Windows Filtering Platform (WFP) APIs.
    Its features include searching for running EDR processes and applying WFP filters to block outbound traffic, adding filters for specific processes, and removing filters either individually or globally.
    The tool includes a custom implementation to avoid file handle access issues with EDR processes by bypassing the CreateFileW API.
    It supports a wide range of EDRs, including Microsoft Defender, Carbon Black, SentinelOne, and more, though further testing on various EDRs is recommended.
    The tool has been tested on Windows 10 and Windows Server 2016, and its usage involves simple commands for blocking or unblocking traffic.
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="EDRSilencer.exe"
    OR
    (
        Processes.process IN ("* blockedr", "* blockedr *")
        NOT Processes.process="*blockedreport*"
    )

    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_edrsilencer_execution_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, parent process, and 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 legitimate administrative tools or security workflows may use similar techniques to block or filter EDR traffic for maintenance or troubleshooting. Verify the context and authorized use before flagging.
references:
    - https://github.com/netero1010/EDRSilencer
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"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: Potential EDRSilencer execution [$process_path$] with the CommandLine [$process$] observed on $dest$.
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process_name
      type: process_name
analytic_story:
    - Security Solution Tampering
asset_type: Endpoint
mitre_attack_id:
    - T1685
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/T1562/snapattack/snapattack.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit

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