Windows Mark Of The Web Bypass

Description

The following analytic identifies a suspicious process that deletes the Mark-of-the-Web (MOTW) data stream. It leverages Sysmon EventCode 23 to detect when a file's Zone.Identifier stream is removed. This activity is significant because it is a common technique used by malware, such as Ave Maria RAT, to bypass security restrictions on files downloaded from the internet. If confirmed malicious, this behavior could allow an attacker to execute potentially harmful files without triggering security warnings, leading to further compromise of the system.

Query · spl

`sysmon`
EventCode IN (23, 26)
TargetFilename = "*:Zone.Identifier"
| stats count min(_time) as firstTime
              max(_time) as lastTime
BY action dest dvc file_path
   file_hash file_name
   file_modify_time process_exec process_guid
   process_id process_name process_path
   signature signature_id user
   user_id vendor_product
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_mark_of_the_web_bypass_filter`

Implementation guide

To successfully implement this search, you need to be ingesting logs with the deleted target file name, process name and process id from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known false positives

  • No false positives have been identified at this time.

Analyst notes

Known false positives: No false positives have been identified at this time.

Raw source Windows Mark Of The Web Bypass · SPL
Esc
Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Windows Mark Of The Web Bypass
id: 8ca13343-7405-4916-a2d1-ae34ce0c28ae
version: 13
creation_date: '2023-08-14'
modification_date: '2026-07-20'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic identifies a suspicious process that deletes the Mark-of-the-Web (MOTW) data stream. It leverages Sysmon EventCode 23 to detect when a file's Zone.Identifier stream is removed. This activity is significant because it is a common technique used by malware, such as Ave Maria RAT, to bypass security restrictions on files downloaded from the internet. If confirmed malicious, this behavior could allow an attacker to execute potentially harmful files without triggering security warnings, leading to further compromise of the system.
data_source:
    - Sysmon EventID 23
    - Sysmon EventID 26
search: |-
    `sysmon`
    EventCode IN (23, 26)
    TargetFilename = "*:Zone.Identifier"
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
    BY action dest dvc file_path
       file_hash file_name
       file_modify_time process_exec process_guid
       process_id process_name process_path
       signature signature_id user
       user_id vendor_product
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_mark_of_the_web_bypass_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the deleted target file name, process name and process id  from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: No false positives have been identified at this time.
references:
    - https://attack.mitre.org/techniques/T1553/005/
    - https://github.com/nmantani/PS-MOTW#remove-motwps1
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - 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: A mark-of-the-web data stream is deleted on $dest$
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: A mark-of-the-web data stream is deleted on $dest$
analytic_story:
    - Quasar RAT
    - Warzone RAT
asset_type: Endpoint
mitre_attack_id:
    - T1553.005
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/T1553.005/mark_of_the_web_bypass/possible-motw-deletion.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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