Suspicious PowerShell Cmdlets

SIGMA detection rule by RedCanary, Sigma formatting by Micah Babinski · GPL-3.0

Many of our PowerShell detection analytics look for cmdlets, methods, and switches that may indicate malicious activity. The following analytic is by no means exhaustive but offers a few valuable examples of suspicious cmdlets and other oft-abused features to look out for. Part of the RedCanary 2024 Threat Detection Report.

title: Suspicious PowerShell Cmdlets
id: 33a86fea-add2-42b3-bccb-96285c619933
status: experimental
description: |
    Many of our PowerShell detection analytics look for cmdlets, methods, and 
    switches that may indicate malicious activity. The following analytic is 
    by no means exhaustive but offers a few valuable examples of suspicious 
    cmdlets and other oft-abused features to look out for. Part of the 
    RedCanary 2024 Threat Detection Report.
references:
    - https://redcanary.com/threat-detection-report/techniques/powershell/
author: RedCanary, Sigma formatting by Micah Babinski
date: 2024/03/21
tags:
    - attack.execution
    - attack.t1059
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\powershell.exe'
        CommandLine|contains:
            - '-nop'
            - '-noni'
            - '-invoke-expression'
            - 'iex'
            - '.downloadstring'
            - 'downloadfile'
    condition: selection
falsepositives:
    - Unknown
level: low

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

be0ba94e-854b-4b0c-8812-e8ca169c848a

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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 ]]

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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.

[[ 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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