Python Function Execution Security Warning Disabled In Excel - Registry

Status: test
Severity: high
Log source: category registry_set, product windows
Author: Nasreddine Bencherchali (Nextron Systems), @Kostastsale
Source: github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685` Disable or Modify Tools

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 13: RegistryEvent (Value Set)

Rule body

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

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    TargetObject|contains: '\Microsoft\Office\'
    TargetObject|endswith: '\Excel\Security\PythonFunctionWarnings'
    Details: 'DWORD (0x00000001)'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Details`	eq	`DWORD (0x00000001)` corpus 40 (sigma 36, chronicle 4)	`field:"Details" kind:eq value:"DWORD (0x00000001)"`
`TargetObject`	ends_with	`\Excel\Security\PythonFunctionWarnings`	`field:"TargetObject" kind:ends_with value:"\Excel\Security\PythonFunctionWarnings"`
`TargetObject`	match	`\Microsoft\Office\` corpus 2 (sigma 2)	`field:"TargetObject" kind:match value:"\Microsoft\Office\"`