Outlook Macro Execution Without Warning Setting Enabled

Hunt Hypothesis

Detects the modification of Outlook security setting to allow unprompted execution of macros.

Detection Rule

Sigma (Original)

title: Outlook Macro Execution Without Warning Setting Enabled
id: e3b50fa5-3c3f-444e-937b-0a99d33731cd
status: test
description: Detects the modification of Outlook security setting to allow unprompted execution of macros.
references:
    - https://www.mdsec.co.uk/2020/11/a-fresh-outlook-on-mail-based-persistence/
    - https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=53
author: '@ScoubiMtl'
date: 2021-04-05
modified: 2023-08-17
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.command-and-control
    - attack.t1137
    - attack.t1008
    - attack.t1546
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|endswith: '\Outlook\Security\Level'
        Details|contains: '0x00000001' # Enable all Macros
    condition: selection
falsepositives:
    - Unlikely
level: high

KQL (Azure Sentinel)

imRegistry
| where RegistryKey endswith "\\Outlook\\Security\\Level" and RegistryValueData contains "0x00000001"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where RegistryKey endswith "\\Outlook\\Security\\Level" and RegistryValueData contains "0x00000001"

Required Data Sources

False Positive Guidance

• Unlikely

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Tactic: Persistence
• Tactic: Command and Control
• Technique: T1137 — T1137
• Technique: T1008 — T1008
• Technique: T1546 — T1546

References

• https://www.mdsec.co.uk/2020/11/a-fresh-outlook-on-mail-based-persistence/
• https://speakerdeck.com/heirhabarov/hunting-for-persistence-via-microsoft-exchange-server-or-outlook?slide=53
• SigmaHQ Rule