Python Function Execution Security Warning Disabled In Excel - Registry

Hunt Hypothesis

Detects changes to the registry value “PythonFunctionWarnings” that would prevent any warnings or alerts from showing when Python functions are about to be executed. Threat actors could run malicious

Detection Rule

Sigma (Original)

title: Python Function Execution Security Warning Disabled In Excel - Registry
id: 17e53739-a1fc-4a62-b1b9-87711c2d5e44
related:
    - id: 023c654f-8f16-44d9-bb2b-00ff36a62af9
      type: similar
status: test
description: |
    Detects changes to the registry value "PythonFunctionWarnings" that would prevent any warnings or alerts from showing when Python functions are about to be executed.
    Threat actors could run malicious code through the new Microsoft Excel feature that allows Python to run within the spreadsheet.
references:
    - https://support.microsoft.com/en-us/office/data-security-and-python-in-excel-33cc88a4-4a87-485e-9ff9-f35958278327
author: Nasreddine Bencherchali (Nextron Systems), @Kostastsale
date: 2024-08-23
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains: '\Microsoft\Office\'
        TargetObject|endswith: '\Excel\Security\PythonFunctionWarnings'
        Details: 'DWORD (0x00000001)'
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imRegistry
| where RegistryKey endswith "\\Microsoft\\Office*" and RegistryKey endswith "\\Excel\\Security\\PythonFunctionWarnings" and RegistryValueData =~ "DWORD (0x00000001)"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where RegistryKey endswith "\\Microsoft\\Office*" and RegistryKey endswith "\\Excel\\Security\\PythonFunctionWarnings" and RegistryValueData =~ "DWORD (0x00000001)"

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Technique: T1685 — T1685

References

• https://support.microsoft.com/en-us/office/data-security-and-python-in-excel-33cc88a4-4a87-485e-9ff9-f35958278327
• SigmaHQ Rule