Sigma to Microsoft Defender XDR

Sigma

title: Base64 Encoding Via Built-In Windows Utility
id: 7c1e0a34-2b5f-4d18-9a63-0c8b1f4e5a71
status: experimental
description: |
    A sample rule for the huntrule.com converter. Detects a built-in utility being asked to
    base64-encode a file, which is a common way to stage data before moving it off a host.
    It exercises the `windash` modifier, where one flag has to be matched in both its dash
    and slash spellings.
author: HuntRule Team
date: 2026-08-01
tags:
    - attack.collection
    - attack.t1560.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\certutil.exe'
        - OriginalFileName: 'CertUtil.exe'
    selection_cli:
        CommandLine|contains|windash: '-encode'
    condition: all of selection_*
falsepositives:
    - Administrative scripts that legitimately encode files
level: medium
license: DRL-1.1

Microsoft Defender XDR · KQL

// huntrule.com — sigma 7c1e0a34-2b5f-4d18-9a63-0c8b1f4e5a71 — HuntRule Team — DRL-1.1
DeviceProcessEvents
| where (FolderPath endswith @"\certutil.exe" or ProcessVersionInfoOriginalFileName =~ @"CertUtil.exe") and (ProcessCommandLine contains @"-encode" or ProcessCommandLine contains @"/encode" or ProcessCommandLine contains @"–encode" or ProcessCommandLine contains @"—encode" or ProcessCommandLine contains @"―encode")

Sigma

title: PowerShell Download Cradle On The Command Line
id: 1f9d4c02-6a77-4e5b-8c31-2d0af7b96e48
status: experimental
description: |
    A sample rule for the huntrule.com converter. Detects the download-and-run pattern where a
    remote payload is fetched and executed in one command. It exercises a value list under a
    single field, which every backend has to expand into its own OR form.
author: HuntRule Team
date: 2026-08-01
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_fetch:
        CommandLine|contains:
            - '.DownloadString('
            - '.DownloadFile('
            - 'Invoke-WebRequest '
            - 'Invoke-RestMethod '
    selection_run:
        CommandLine|contains:
            - '| IEX'
            - 'IEX ('
            - 'Invoke-Expression'
    condition: all of selection_*
falsepositives:
    - Installers and package managers that fetch and run their own payloads
level: high
license: DRL-1.1

Microsoft Defender XDR · KQL

// huntrule.com — sigma 1f9d4c02-6a77-4e5b-8c31-2d0af7b96e48 — HuntRule Team — DRL-1.1
DeviceProcessEvents
| where (ProcessCommandLine contains @".DownloadString(" or ProcessCommandLine contains @".DownloadFile(" or ProcessCommandLine contains @"Invoke-WebRequest " or ProcessCommandLine contains @"Invoke-RestMethod ") and (ProcessCommandLine contains @"| IEX" or ProcessCommandLine contains @"IEX (" or ProcessCommandLine contains @"Invoke-Expression")

Sigma

title: Registry Import With A Suspicious Path
id: 5b3a8e91-4c26-4f70-b1d8-6e97c30a2f5d
status: experimental
description: |
    A sample rule for the huntrule.com converter. Detects a registry import whose argument does
    not look like an ordinary file path. It exercises a regular expression alongside a `not`
    filter, so the report has both a regex to check against the target's engine and a negated
    branch to place.
author: HuntRule Team
date: 2026-08-01
tags:
    - attack.defense-evasion
    - attack.t1112
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\regedit.exe'
        - OriginalFileName: 'REGEDIT.EXE'
    selection_cli:
        CommandLine|contains: '.reg'
        CommandLine|re: ':[^ \\]'
    filter_flags:
        CommandLine|contains|windash:
            - ' -e '
            - ' -a '
    condition: all of selection_* and not filter_flags
falsepositives:
    - Scripted registry maintenance
level: high
license: DRL-1.1

Microsoft Defender XDR · KQL

// huntrule.com — sigma 5b3a8e91-4c26-4f70-b1d8-6e97c30a2f5d — HuntRule Team — DRL-1.1
DeviceProcessEvents
| where (FolderPath endswith @"\regedit.exe" or ProcessVersionInfoOriginalFileName =~ @"REGEDIT.EXE") and ProcessCommandLine contains @".reg" and ProcessCommandLine matches regex @":[^ \\]" and (not(ProcessCommandLine contains @" -e " or ProcessCommandLine contains @" /e " or ProcessCommandLine contains @" –e " or ProcessCommandLine contains @" —e " or ProcessCommandLine contains @" ―e " or ProcessCommandLine contains @" -a " or ProcessCommandLine contains @" /a " or ProcessCommandLine contains @" –a " or ProcessCommandLine contains @" —a " or ProcessCommandLine contains @" ―a "))

Sigma

title: File Copy Through The Print Utility
id: 3e6c17b8-9f40-4a2d-85e1-7b4d0c9a6f23
status: experimental
description: |
    A sample rule for the huntrule.com converter. Detects the print utility being used to copy an
    executable rather than to print. It exercises `startswith` together with `contains|all`, where
    several substrings must all appear in one field.
author: HuntRule Team
date: 2026-08-01
tags:
    - attack.defense-evasion
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\print.exe'
        CommandLine|startswith: 'print'
        CommandLine|contains|all:
            - '/D'
            - '.exe'
    filter_self:
        CommandLine|contains: 'print.exe'
    condition: selection and not filter_self
falsepositives:
    - Printing a file whose name ends in .exe
level: medium
license: DRL-1.1

Microsoft Defender XDR · KQL

// huntrule.com — sigma 3e6c17b8-9f40-4a2d-85e1-7b4d0c9a6f23 — HuntRule Team — DRL-1.1
DeviceProcessEvents
| where FolderPath endswith @"\print.exe" and ProcessCommandLine startswith @"print" and ProcessCommandLine contains @"/D" and ProcessCommandLine contains @".exe" and (ProcessCommandLine !contains @"print.exe")