splunk_escuTTP

Windows Alternate DataStream - Executable Content

The following analytic detects the writing of data with an IMPHASH value to an Alternate Data Stream (ADS) in the NTFS file system. It leverages Sysmon Event ID 15 and regex to identify files with a Portable Executable (PE) structure. This activity is significant as it may indicate a threat actor staging malicious code in hidden areas for persistence or future execution. If confirmed malicious, this could allow attackers to execute hidden code, maintain persistence, or escalate privileges within the environment.

MITRE ATT&CK

T1564.004

Detection Query

`sysmon` EventCode=15 IMPHASH!=00000000000000000000000000000000 | regex TargetFilename="(?<!\/)\b\w+(\.\w+)?:\w+(\.\w+)?$" | eval file_name = replace(TargetFilename,"(.*\\\)",""), process = Image , file_path = TargetFilename, file_hash = coalesce(SHA256,SHA1,MD5,Hash) | stats count min(_time) as firstTime max(_time) as lastTime by dest dvc file_hash file_name file_path process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Contents Image | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_alternate_datastream___executable_content_filter`

Author

Steven Dick, Teoderick Contreras, Splunk

Created

2026-03-10

Data Sources

Sysmon EventID 15

References

Tags

Windows Defense Evasion Tactics

Raw Content

name: Windows Alternate DataStream - Executable Content
id: a258bf2a-34fd-4986-8086-78f506e00206
version: 11
date: '2026-03-10'
author: Steven Dick, Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects the writing of data with an IMPHASH value to an Alternate Data Stream (ADS) in the NTFS file system. It leverages Sysmon Event ID 15 and regex to identify files with a Portable Executable (PE) structure. This activity is significant as it may indicate a threat actor staging malicious code in hidden areas for persistence or future execution. If confirmed malicious, this could allow attackers to execute hidden code, maintain persistence, or escalate privileges within the environment.
data_source:
    - Sysmon EventID 15
search: '`sysmon` EventCode=15 IMPHASH!=00000000000000000000000000000000 | regex TargetFilename="(?<!\/)\b\w+(\.\w+)?:\w+(\.\w+)?$" | eval file_name = replace(TargetFilename,"(.*\\\)",""), process = Image , file_path = TargetFilename, file_hash = coalesce(SHA256,SHA1,MD5,Hash) | stats count min(_time) as firstTime max(_time) as lastTime by dest dvc file_hash file_name file_path process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Contents Image | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_alternate_datastream___executable_content_filter`'
how_to_implement: Target environment must ingest Sysmon data, specifically Event ID 15, and import hashing/imphash must be enabled within Sysmon.
known_false_positives: No false positives have been identified at this time.
references:
    - https://car.mitre.org/analytics/CAR-2020-08-001/
    - https://blogs.juniper.net/en-us/threat-research/bitpaymer-ransomware-hides-behind-windows-alternate-data-streams
    - https://twitter.com/0xrawsec/status/1002478725605273600?s=21
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 ("$dest$") 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: Base64 content written to an NTFS alternate data stream in $dest$, see command field for details.
    risk_objects:
        - field: dest
          type: system
          score: 50
    threat_objects:
        - field: file_name
          type: file_name
        - field: file_hash
          type: file_hash
tags:
    analytic_story:
        - Windows Defense Evasion Tactics
    asset_type: Endpoint
    mitre_attack_id:
        - T1564.004
    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/T1564.004/ads_abuse/ads_abuse_sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog