sigmahighHunting

Suspicious PowerShell IEX Execution Patterns

Detects suspicious ways to run Invoke-Execution using IEX alias

MITRE ATT&CK

execution

Detection Query

selection_combined_1:
  Image|endswith:
    - \powershell.exe
    - \pwsh.exe
  CommandLine|contains:
    - " | iex;"
    - " | iex "
    - " | iex}"
    - " | IEX ;"
    - " | IEX -Error"
    - " | IEX (new"
    - ");IEX "
selection_combined_2:
  CommandLine|contains:
    - ::FromBase64String
    - ".GetString([System.Convert]::"
selection_standalone:
  CommandLine|contains:
    - )|iex;$
    - );iex($
    - );iex $
    - " | IEX | "
    - ' | iex\"'
condition: all of selection_combined_* or selection_standalone

Author

Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)

Created

2022-03-24

Data Sources

windowsProcess Creation Events

Platforms

windows

References

Tags

attack.executionattack.t1059.001

Raw Content

title: Suspicious PowerShell IEX Execution Patterns
id: 09576804-7a05-458e-a817-eb718ca91f54
status: test
description: Detects suspicious ways to run Invoke-Execution using IEX alias
references:
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/invoke-expression?view=powershell-7.2
    - https://www.huntress.com/blog/slashandgrab-screen-connect-post-exploitation-in-the-wild-cve-2024-1709-cve-2024-1708
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2022-03-24
modified: 2022-11-28
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_combined_1:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        CommandLine|contains:
            - ' | iex;'
            - ' | iex '
            - ' | iex}'
            - ' | IEX ;'
            - ' | IEX -Error'
            - ' | IEX (new'
            - ');IEX '
    selection_combined_2:
        CommandLine|contains:
            - '::FromBase64String'
            - '.GetString([System.Convert]::'
    selection_standalone:
        CommandLine|contains:
            - ')|iex;$'
            - ');iex($'
            - ');iex $'
            - ' | IEX | '
            - ' | iex\"'
    condition: all of selection_combined_* or selection_standalone
falsepositives:
    - Legitimate scripts that use IEX
level: high