Suspicious Outlook Security Settings Updated - Registry (via registry_set)

title: Suspicious Outlook Security Settings Updated - Registry (via registry_set)
id: 99f85769-f8ba-5c12-a161-a7b32d50a0ef
status: stable
description: This rule detects changes to the registry values related to outlook security settings
references:
    - https://attack.mitre.org/techniques/T1137/
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1137/T1137.md
    - https://learn.microsoft.com/en-us/outlook/troubleshoot/security/information-about-email-security-settings
author: Huntrule Team
date: 2026-01-02
tags:
    - attack.persistence
    - attack.t1137
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains|all:
            - '\SOFTWARE\Microsoft\Office\'
            - '\Outlook\Security\'
    filter_main_outlook:
        Image|startswith:
            - 'C:\Program Files\Microsoft Office\'
            - 'C:\Program Files (x86)\Microsoft Office\'
        Image|endswith: '\OUTLOOK.EXE'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium