Sigma rule: Net WebClient Casing Anomalies

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-856403c864b3, updated 2023-01-05T00:00:00.000Z.

Rule

Title
Net WebClient Casing Anomalies
Status
test
Level
high
Author
Florian Roth (Nextron Systems)
Date
2022-05-24
Modified
2023-01-05
File
rules/windows/process_creation/proc_creation_win_powershell_webclient_casing.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

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

Log source

product
windows
category
process_creation

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_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.execution
  • attack.t1059.001

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_webclient_casing.yml

Sources and licences

  • SigmaHQ

    "Net WebClient Casing Anomalies" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_webclient_casing.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Net WebClient Casing Anomalies",
entity page, dataset version ref-856403c864b3, updated 2023-01-05T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/c86133ad-4725-4bd0-8170-210788e0a7ba (accessed 2026-11-03).
Underlying source: SigmaHQ rule c86133ad-4725-4bd0-8170-210788e0a7ba, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.