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Detection rules › Sigma

Python Function Execution Security Warning Disabled In Excel

Status
test
Severity
high
Log source
product windows, category process_creation
Author
@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

TacticTechniques
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: Python Function Execution Security Warning Disabled In Excel
id: 023c654f-8f16-44d9-bb2b-00ff36a62af9
related:
    - id: 17e53739-a1fc-4a62-b1b9-87711c2d5e44
      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: '@Kostastsale'
date: 2023-08-22
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - '\Microsoft\Office\'
            - '\Excel\Security'
            - 'PythonFunctionWarnings'
        CommandLine|contains: ' 0'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    CommandLine|contains|all:
        - '\Microsoft\Office\'
        - '\Excel\Security'
        - 'PythonFunctionWarnings'
    CommandLine|contains: ' 0'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • 0 corpus 3 (sigma 3)
  • PythonFunctionWarnings
  • \Excel\Security
  • \Microsoft\Office\