Disable Macro Runtime Scan Scope

Hunt Hypothesis

Detects tampering with the MacroRuntimeScanScope registry key to disable runtime scanning of enabled macros

Detection Rule

Sigma (Original)

title: Disable Macro Runtime Scan Scope
id: ab871450-37dc-4a3a-997f-6662aa8ae0f1
description: Detects tampering with the MacroRuntimeScanScope registry key to disable runtime scanning of enabled macros
status: test
date: 2022-10-25
modified: 2023-08-17
author: Nasreddine Bencherchali (Nextron Systems)
references:
    - https://www.microsoft.com/en-us/security/blog/2018/09/12/office-vba-amsi-parting-the-veil-on-malicious-macros/
    - https://admx.help/?Category=Office2016&Policy=office16.Office.Microsoft.Policies.Windows::L_MacroRuntimeScanScope
    - https://github.com/S3cur3Th1sSh1t/OffensiveVBA/blob/28cc6a2802d8176195ac19b3c8e9a749009a82a3/src/AMSIbypasses.vba
tags:
    - attack.defense-impairment
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject|contains|all:
            - '\SOFTWARE\'
            - '\Microsoft\Office\'
            - '\Common\Security'
        TargetObject|endswith: '\MacroRuntimeScanScope'
        Details: DWORD (0x00000000)
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey endswith "\\SOFTWARE*" and RegistryKey endswith "\\Microsoft\\Office*" and RegistryKey contains "\\Common\\Security") and RegistryKey endswith "\\MacroRuntimeScanScope" and RegistryValueData =~ "DWORD (0x00000000)"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where (RegistryKey endswith "\\SOFTWARE*" and RegistryKey endswith "\\Microsoft\\Office*" and RegistryKey contains "\\Common\\Security") and RegistryKey endswith "\\MacroRuntimeScanScope" and RegistryValueData =~ "DWORD (0x00000000)"

Required Data Sources

False Positive Guidance

• Unknown

References

• https://www.microsoft.com/en-us/security/blog/2018/09/12/office-vba-amsi-parting-the-veil-on-malicious-macros/
• https://admx.help/?Category=Office2016&Policy=office16.Office.Microsoft.Policies.Windows::L_MacroRuntimeScanScope
• https://github.com/S3cur3Th1sSh1t/OffensiveVBA/blob/28cc6a2802d8176195ac19b3c8e9a749009a82a3/src/AMSIbypasses.vba
• SigmaHQ Rule