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Detection: Windows Mark Of The Web Bypass

Updated Date: 2026-05-13 ID: 8ca13343-7405-4916-a2d1-ae34ce0c28ae Author: Teoderick Contreras, Splunk Type: TTP Product: Splunk Enterprise Security

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.

 1`sysmon` EventCode=23 TargetFilename = "*:Zone.Identifier"
 2  
 3| stats count min(_time) as firstTime, max(_time) as lastTime
 4    BY action dest dvc
 5       file_path file_hash file_name
 6       file_modify_time process_exec process_guid
 7       process_id process_name process_path
 8       signature signature_id user
 9       user_id vendor_product
10  
11| `security_content_ctime(firstTime)`
12  
13| `security_content_ctime(lastTime)`
14  
15| `windows_mark_of_the_web_bypass_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 23 Windows icon Windows 'XmlWinEventLog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
sysmon (source=WinEventLog:Microsoft-Windows-Sysmon/Operational OR source=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational OR source=Syslog:Linux-Sysmon/Operational)
windows_mark_of_the_web_bypass_filter search *
windows_mark_of_the_web_bypass_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1553.005 Mark-of-the-Web Bypass Defense Impairment
Exploitation
DE.CM
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Finding (Notable) Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Intermediate Finding (Risk Event) Yes
TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

Implementation

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.

Associated Analytic Story

Finding

Title Entity Field Entity Type Risk Score
A mark-of-the-web data stream is deleted on $dest$ user user 50

Intermediate Findings

Message Entity Field Entity Type Risk Score
A mark-of-the-web data stream is deleted on $dest$ dest system 50

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 12