Suspicious MSHTA Child Process

SIGMA detection rule by Michael Haag · GPL-2.0

Detects a suspicious process spawning from an "mshta.exe" process, which could be indicative of a malicious HTA script execution

title: Suspicious MSHTA Child Process
id: 49fcee15-4a91-2599-357b-6a1abe3d7cf4
related:
    - id: 03cc0c25-389f-4bf8-b48d-11878079f1ca
      type: derived
status: test
description: Detects a suspicious process spawning from an "mshta.exe" process, which could be indicative of a malicious HTA script execution
references:
    - https://www.trustedsec.com/july-2015/malicious-htas/
author: Michael Haag
date: 2019-01-16
modified: 2023-02-06
tags:
    - attack.stealth
    - attack.t1218.005
    - car.2013-02-003
    - car.2013-03-001
    - car.2014-04-003
logsource:
    category: process_creation
    product: windows
detection:
    process_creation:
        EventID: 4688
        Channel: Security
    selection_parent:
        ParentProcessName|endswith: \mshta.exe
    selection_child:
        - NewProcessName|endswith:
              - \cmd.exe
              - \powershell.exe
              - \pwsh.exe
              - \wscript.exe
              - \cscript.exe
              - \sh.exe
              - \bash.exe
              - \reg.exe
              - \regsvr32.exe
              - \bitsadmin.exe
        - OriginalFileName:
              - Cmd.Exe
              - PowerShell.EXE
              - pwsh.dll
              - wscript.exe
              - cscript.exe
              - Bash.exe
              - reg.exe
              - REGSVR32.EXE
              - bitsadmin.exe
    condition: process_creation and (all of selection*)
falsepositives:
    - Printer software / driver installations
    - HP software
level: high
ruletype: Sigma

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

d32e31be-4c39-4045-9a92-fffcff908923

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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 ]]

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