Office Macro File Creation From Suspicious Process

SIGMA detection rule by frack113, Nasreddine Bencherchali (Nextron Systems) · NOASSERTION

Detects the creation of a office macro file from a a suspicious process

title: Office Macro File Creation From Suspicious Process
id: b1c50487-1967-4315-a026-6491686d860e
status: test
description: Detects the creation of a office macro file from a a suspicious process
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1566.001/T1566.001.md
    - https://learn.microsoft.com/en-us/deployoffice/compat/office-file-format-reference
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2022-01-23
modified: 2023-02-22
tags:
    - attack.initial-access
    - attack.t1566.001
logsource:
    category: file_event
    product: windows
    definition: 'Requirements: The "ParentImage" field is not available by default on EID 11 of Sysmon logs. To be able to use this rule to the full extent you need to enriche the log with additional ParentImage data'
detection:
    selection_cmd:
        - Image|endswith:
              - '\cscript.exe'
              - '\mshta.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
        # Note: ParentImage is a custom field and is not available by default on Sysmon EID 11
        - ParentImage|endswith:
              - '\cscript.exe'
              - '\mshta.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
    selection_ext:
        TargetFilename|endswith:
            - '.docm'
            - '.dotm'
            - '.xlsm'
            - '.xltm'
            - '.potm'
            - '.pptm'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

a4da1556-ad70-405c-811d-d1b69b08bf31

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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