Convert indexed Sigma rules into analyst-ready detections.

title: Creation Of a Suspicious ADS File Outside a Browser Download
id: 573df571-a223-43bc-846e-3f98da481eca
status: test
description: Detects the creation of a suspicious ADS (Alternate Data Stream) file by software other than browsers
references:
    - https://www.bleepingcomputer.com/news/security/exploited-windows-zero-day-lets-javascript-files-bypass-security-warnings/
author: frack113
date: 2022-10-22
modified: 2023-06-12
tags:
    - attack.defense-evasion
logsource:
    product: windows
    category: create_stream_hash
detection:
    selection:
        Contents|startswith: '[ZoneTransfer]  ZoneId=3'
        TargetFilename|endswith: ':Zone.Identifier'
        TargetFilename|contains:
            - '.exe'
            - '.scr'
            - '.bat'
            - '.cmd'
            - '.docx'
            - '.hta'
            - '.jse'
            - '.lnk'
            - '.pptx'
            - '.ps'
            - '.reg'
            - '.sct'
            - '.vb'
            - '.wsc'
            - '.wsf'
            - '.xlsx'
    filter_optional_brave:
        Image|endswith: '\brave.exe'
    filter_optional_chrome:
        Image:
            - 'C:\Program Files\Google\Chrome\Application\chrome.exe'
            - 'C:\Program Files (x86)\Google\Chrome\Application\chrome.exe'
    filter_optional_firefox:
        Image:
            - 'C:\Program Files\Mozilla Firefox\firefox.exe'
            - 'C:\Program Files (x86)\Mozilla Firefox\firefox.exe'
    filter_optional_ie:
        Image:
            - 'C:\Program Files (x86)\Internet Explorer\iexplore.exe'
            - 'C:\Program Files\Internet Explorer\iexplore.exe'
    filter_optional_maxthon:
        Image|endswith: '\maxthon.exe'
    filter_optional_edge_1:
        - Image|startswith: 'C:\Program Files (x86)\Microsoft\EdgeWebView\Application\'
        - Image|endswith: '\WindowsApps\MicrosoftEdge.exe'
        - Image:
              - 'C:\Program Files (x86)\Microsoft\Edge\Application\msedge.exe'
              - 'C:\Program Files\Microsoft\Edge\Application\msedge.exe'
    filter_optional_edge_2:
        Image|startswith:
            - 'C:\Program Files (x86)\Microsoft\EdgeCore\'
            - 'C:\Program Files\Microsoft\EdgeCore\'
        Image|endswith:
            - '\msedge.exe'
            - '\msedgewebview2.exe'
    filter_optional_opera:
        Image|endswith: '\opera.exe'
    filter_optional_safari:
        Image|endswith: '\safari.exe'
    filter_optional_seamonkey:
        Image|endswith: '\seamonkey.exe'
    filter_optional_vivaldi:
        Image|endswith: '\vivaldi.exe'
    filter_optional_whale:
        Image|endswith: '\whale.exe'
    filter_optional_snipping_tool:
        Image|startswith: 'C:\Program Files\WindowsApps\Microsoft.ScreenSketch_'
        Image|endswith: '\SnippingTool\SnippingTool.exe'
        TargetFilename|startswith: 'C:\Users\'
        TargetFilename|contains|all:
            - '\AppData\Local\Packages\Microsoft.ScreenSketch_'
            - '\TempState\Screenshot '
        TargetFilename|endswith: '.png:Zone.Identifier'
    condition: selection and not 1 of filter_optional_*
falsepositives:
    - Other legitimate browsers not currently included in the filter (please add them)
    - Legitimate downloads via scripting or command-line tools (Investigate to determine if it's legitimate)
level: medium