Suspicious Binary In User Directory Spawned From Office Application

SIGMA detection rule by Jason Lynch · NOASSERTION

Detects an executable in the users directory started from one of the Microsoft Office suite applications (Word, Excel, PowerPoint, Publisher, Visio)

title: Suspicious Binary In User Directory Spawned From Office Application
id: aa3a6f94-890e-4e22-b634-ffdfd54792cc
status: test
description: Detects an executable in the users directory started from one of the Microsoft Office suite applications (Word, Excel, PowerPoint, Publisher, Visio)
references:
    - https://blog.morphisec.com/fin7-not-finished-morphisec-spots-new-campaign
    - https://www.virustotal.com/gui/file/23160972c6ae07f740800fa28e421a81d7c0ca5d5cab95bc082b4a986fbac57
author: Jason Lynch
date: 2019-04-02
modified: 2023-02-04
tags:
    - attack.execution
    - attack.t1204.002
    - attack.g0046
    - car.2013-05-002
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\WINWORD.EXE'
            - '\EXCEL.EXE'
            - '\POWERPNT.exe'
            - '\MSPUB.exe'
            - '\VISIO.exe'
            - '\MSACCESS.exe'
            - '\EQNEDT32.exe'
            # - '\OUTLOOK.EXE' too many FPs
        Image|startswith: 'C:\users\'
        Image|endswith: '.exe'
    filter:
        Image|endswith: '\Teams.exe'
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

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

8ce876b9-7c86-494f-8fed-ea54ad83b89c

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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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