splunk_escuAnomaly

Windows Alternate Data Stream Created Over Local Share

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.

Detection Query

`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`

Author

Onur Mustafa Erdogan, Splunk

Data Sources

Windows Event Log Security 5145

References

Raw Content

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+$"
    | fillnull
    | rename IpAddress as dest_ip
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
      by dest dest_ip
         ShareName ShareLocalPath RelativeTargetName
         AccessMask src_user
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_alternate_data_stream_created_over_local_share_filter`
how_to_implement: |-
    To successfully implement this search, you need to be ingesting Windows Security Event Logs with EventCode 5145 enabled.
    The Windows TA is also required.
    Enable Object Access auditing (success/failure) for File Share in group policy so that RelativeTargetName and IpAddress are populated.
known_false_positives: |-
    Backup, replication, or file-sync software may occasionally write alternate data streams over administrative shares.
    Loopback (127.0.0.1) access to a local share is rare for legitimate software, tune by ShareName or src_user as needed for your environment.
references:
    - https://www.cyderes.com/howler-cell/rogueplanet-windows-zero-day
    - https://www.threatlocker.com/blog/nightmareeclipse-releases-new-poc-shieldbreak-exploits-same-weakness-as-rogueplanet
drilldown_searches:
    - name: View the detection results for - "$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"
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
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/emerging_threats/ShieldBreak/ads_over_local_share.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit