Potential CVE-2021-40444 Exploitation Attempt

SIGMA detection rule by Florian Roth (Nextron Systems), @neonprimetime · NOASSERTION

Detects potential exploitation of CVE-2021-40444 via suspicious process patterns seen in in-the-wild exploitations

title: Potential CVE-2021-40444 Exploitation Attempt
id: 894397c6-da03-425c-a589-3d09e7d1f750
status: test
description: Detects potential exploitation of CVE-2021-40444 via suspicious process patterns seen in in-the-wild exploitations
references:
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444
    - https://twitter.com/neonprimetime/status/1435584010202255375
    - https://www.joesandbox.com/analysis/476188/1/iochtml
author: Florian Roth (Nextron Systems), @neonprimetime
date: 2021-09-08
modified: 2023-02-04
tags:
    - attack.execution
    - attack.t1059
    - cve.2021-40444
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\control.exe'
        ParentImage|endswith:
            - '\winword.exe'
            - '\powerpnt.exe'
            - '\excel.exe'
    filter:
        CommandLine|endswith:
            - '\control.exe input.dll'
            - '\control.exe" input.dll'
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

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

d49c6177-f594-46b2-8a5a-5b61afdbf593

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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

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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.

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

[[ currentRule.title ]]

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