Windows Alternate Data Stream Created Over Local Share

name: Windows Alternate Data Stream Created Over Local Share
id: e974a5c9-cbe9-4b4a-8fba-b55e7dbc8259
version: 1
creation_date: '2026-08-19'
modification_date: '2026-08-19'
author: Onur Mustafa Erdogan, Splunk
status: production
type: Anomaly
description: |-
    The following analytic detects the creation of an NTFS alternate data stream (ADS) accessed over a local administrative share targeting the loopback address (127.0.0.1).
    It leverages Windows Security Event Logs with EventCode 5145 to identify this activity.
    Legitimate local processes access files directly rather than through a local SMB share.
    This behavior is a hallmark of the ShieldBreak exploit, which abuses a symbolic link swap through a loopback share to redirect a privileged, Defender-driven write into an alternate data stream on a system-owned file, ultimately landing attacker content in C:\Windows\System32.
    If confirmed malicious, this activity indicates an in-progress local privilege escalation attempt and should be investigated immediately.
data_source:
    - Windows Event Log Security 5145
search: |-
    `wineventlog_security`
    EventCode=5145
    IpAddress="127.0.0.1"
    ObjectType="File"
    | regex RelativeTargetName="(?i)\:\w+$"
    | fillnull
    | rename IpAddress as dest_ip
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
      by dest dest_ip
         ShareName ShareLocalPath RelativeTargetName
         AccessMask src_user
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_alternate_data_stream_created_over_local_share_filter`
how_to_implement: |-
    To successfully implement this search, you need to be ingesting Windows Security Event Logs with EventCode 5145 enabled.
    The Windows TA is also required.
    Enable Object Access auditing (success/failure) for File Share in group policy so that RelativeTargetName and IpAddress are populated.
known_false_positives: |-
    Backup, replication, or file-sync software may occasionally write alternate data streams over administrative shares.
    Loopback (127.0.0.1) access to a local share is rare for legitimate software, tune by ShareName or src_user as needed for your environment.
references:
    - https://www.cyderes.com/howler-cell/rogueplanet-windows-zero-day
    - https://www.threatlocker.com/blog/nightmareeclipse-releases-new-poc-shieldbreak-exploits-same-weakness-as-rogueplanet
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: An alternate data stream $RelativeTargetName$ was created over a loopback local share on $dest$
threat_objects:
    - field: dest
      type: system
    - field: RelativeTargetName
      type: file_path
    - field: src_user
      type: user
analytic_story:
    - RoguePlanet
asset_type: Endpoint
mitre_attack_id:
    - T1564.004
    - T1021.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint