Net WebClient Casing Anomalies

title: Net WebClient Casing Anomalies
id: c86133ad-4725-4bd0-8170-210788e0a7ba
status: test
description: Detects PowerShell command line contents that include a suspicious abnormal casing in the Net.Webclient (e.g. nEt.WEbCliEnT) string as used in obfuscation techniques
references:
    - https://app.any.run/tasks/b9040c63-c140-479b-ad59-f1bb56ce7a97/
author: Florian Roth (Nextron Systems)
date: 2022-05-24
modified: 2023-01-05
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_encoded:
        CommandLine|contains:
            - 'TgBlAFQALgB3AEUAQg'
            - '4AZQBUAC4AdwBFAEIA'
            - 'OAGUAVAAuAHcARQBCA'
            - 'bgBFAHQALgB3AGUAYg'
            - '4ARQB0AC4AdwBlAGIA'
            - 'uAEUAdAAuAHcAZQBiA'
            - 'TgBFAHQALgB3AGUAYg'
            - 'OAEUAdAAuAHcAZQBiA'
            - 'bgBlAFQALgB3AGUAYg'
            - '4AZQBUAC4AdwBlAGIA'
            - 'uAGUAVAAuAHcAZQBiA'
            - 'TgBlAFQALgB3AGUAYg'
            - 'OAGUAVAAuAHcAZQBiA'
            - 'bgBFAFQALgB3AGUAYg'
            - '4ARQBUAC4AdwBlAGIA'
            - 'uAEUAVAAuAHcAZQBiA'
            - 'bgBlAHQALgBXAGUAYg'
            - '4AZQB0AC4AVwBlAGIA'
            - 'uAGUAdAAuAFcAZQBiA'
            - 'bgBFAHQALgBXAGUAYg'
            - '4ARQB0AC4AVwBlAGIA'
            - 'uAEUAdAAuAFcAZQBiA'
            - 'TgBFAHQALgBXAGUAYg'
            - 'OAEUAdAAuAFcAZQBiA'
            - 'bgBlAFQALgBXAGUAYg'
            - '4AZQBUAC4AVwBlAGIA'
            - 'uAGUAVAAuAFcAZQBiA'
            - 'TgBlAFQALgBXAGUAYg'
            - 'OAGUAVAAuAFcAZQBiA'
            - 'bgBFAFQALgBXAGUAYg'
            - '4ARQBUAC4AVwBlAGIA'
            - 'uAEUAVAAuAFcAZQBiA'
            - 'bgBlAHQALgB3AEUAYg'
            - '4AZQB0AC4AdwBFAGIA'
            - 'uAGUAdAAuAHcARQBiA'
            - 'TgBlAHQALgB3AEUAYg'
            - 'OAGUAdAAuAHcARQBiA'
            - 'bgBFAHQALgB3AEUAYg'
            - '4ARQB0AC4AdwBFAGIA'
            - 'uAEUAdAAuAHcARQBiA'
            - 'TgBFAHQALgB3AEUAYg'
            - 'OAEUAdAAuAHcARQBiA'
            - 'bgBlAFQALgB3AEUAYg'
            - '4AZQBUAC4AdwBFAGIA'
            - 'uAGUAVAAuAHcARQBiA'
            - 'TgBlAFQALgB3AEUAYg'
            - 'OAGUAVAAuAHcARQBiA'
            - 'bgBFAFQALgB3AEUAYg'
            - '4ARQBUAC4AdwBFAGIA'
            - 'uAEUAVAAuAHcARQBiA'
            - 'TgBFAFQALgB3AEUAYg'
            - 'OAEUAVAAuAHcARQBiA'
            - 'bgBlAHQALgBXAEUAYg'
            - '4AZQB0AC4AVwBFAGIA'
            - 'uAGUAdAAuAFcARQBiA'
            - 'TgBlAHQALgBXAEUAYg'
            - 'OAGUAdAAuAFcARQBiA'
            - 'bgBFAHQALgBXAEUAYg'
            - '4ARQB0AC4AVwBFAGIA'
            - 'uAEUAdAAuAFcARQBiA'
            - 'TgBFAHQALgBXAEUAYg'
            - 'OAEUAdAAuAFcARQBiA'
            - 'bgBlAFQALgBXAEUAYg'
            - '4AZQBUAC4AVwBFAGIA'
            - 'uAGUAVAAuAFcARQBiA'
            - 'TgBlAFQALgBXAEUAYg'
            - 'OAGUAVAAuAFcARQBiA'
            - 'bgBFAFQALgBXAEUAYg'
            - '4ARQBUAC4AVwBFAGIA'
            - 'uAEUAVAAuAFcARQBiA'
            - 'TgBFAFQALgBXAEUAYg'
            - 'OAEUAVAAuAFcARQBiA'
            - 'bgBlAHQALgB3AGUAQg'
            - '4AZQB0AC4AdwBlAEIA'
            - 'uAGUAdAAuAHcAZQBCA'
            - 'TgBlAHQALgB3AGUAQg'
            - 'OAGUAdAAuAHcAZQBCA'
            - 'bgBFAHQALgB3AGUAQg'
            - '4ARQB0AC4AdwBlAEIA'
            - 'uAEUAdAAuAHcAZQBCA'
            - 'TgBFAHQALgB3AGUAQg'
            - 'OAEUAdAAuAHcAZQBCA'
            - 'bgBlAFQALgB3AGUAQg'
            - '4AZQBUAC4AdwBlAEIA'
            - 'uAGUAVAAuAHcAZQBCA'
            - 'TgBlAFQALgB3AGUAQg'
            - 'OAGUAVAAuAHcAZQBCA'
            - 'bgBFAFQALgB3AGUAQg'
            - '4ARQBUAC4AdwBlAEIA'
            - 'uAEUAVAAuAHcAZQBCA'
            - 'TgBFAFQALgB3AGUAQg'
            - 'OAEUAVAAuAHcAZQBCA'
            - 'bgBlAHQALgBXAGUAQg'
            - '4AZQB0AC4AVwBlAEIA'
            - 'uAGUAdAAuAFcAZQBCA'
            - 'TgBlAHQALgBXAGUAQg'
            - 'OAGUAdAAuAFcAZQBCA'
            - 'bgBFAHQALgBXAGUAQg'
            - '4ARQB0AC4AVwBlAEIA'
            - 'uAEUAdAAuAFcAZQBCA'
            - 'TgBFAHQALgBXAGUAQg'
            - 'OAEUAdAAuAFcAZQBCA'
            - 'bgBlAFQALgBXAGUAQg'
            - '4AZQBUAC4AVwBlAEIA'
            - 'uAGUAVAAuAFcAZQBCA'
            - 'TgBlAFQALgBXAGUAQg'
            - 'OAGUAVAAuAFcAZQBCA'
            - 'bgBFAFQALgBXAGUAQg'
            - '4ARQBUAC4AVwBlAEIA'
            - 'uAEUAVAAuAFcAZQBCA'
            - 'TgBFAFQALgBXAGUAQg'
            - 'OAEUAVAAuAFcAZQBCA'
            - 'bgBlAHQALgB3AEUAQg'
            - '4AZQB0AC4AdwBFAEIA'
            - 'uAGUAdAAuAHcARQBCA'
            - 'TgBlAHQALgB3AEUAQg'
            - 'OAGUAdAAuAHcARQBCA'
            - 'bgBFAHQALgB3AEUAQg'
            - '4ARQB0AC4AdwBFAEIA'
            - 'uAEUAdAAuAHcARQBCA'
            - 'TgBFAHQALgB3AEUAQg'
            - 'OAEUAdAAuAHcARQBCA'
            - 'bgBlAFQALgB3AEUAQg'
            - 'uAGUAVAAuAHcARQBCA'
            - 'bgBFAFQALgB3AEUAQg'
            - '4ARQBUAC4AdwBFAEIA'
            - 'uAEUAVAAuAHcARQBCA'
            - 'TgBFAFQALgB3AEUAQg'
            - 'OAEUAVAAuAHcARQBCA'
            - 'TgBlAHQALgBXAEUAQg'
            - '4AZQB0AC4AVwBFAEIA'
            - 'OAGUAdAAuAFcARQBCA'
            - 'bgBFAHQALgBXAEUAQg'
            - '4ARQB0AC4AVwBFAEIA'
            - 'uAEUAdAAuAFcARQBCA'
            - 'TgBFAHQALgBXAEUAQg'
            - 'OAEUAdAAuAFcARQBCA'
            - 'bgBlAFQALgBXAEUAQg'
            - '4AZQBUAC4AVwBFAEIA'
            - 'uAGUAVAAuAFcARQBCA'
            - 'TgBlAFQALgBXAEUAQg'
            - 'OAGUAVAAuAFcARQBCA'
            - 'bgBFAFQALgBXAEUAQg'
            - '4ARQBUAC4AVwBFAEIA'
            - 'uAEUAVAAuAFcARQBCA'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high