Detectionhightest

Suspicious Download from Office Domain

Detects suspicious ways to download files from Microsoft domains that are used to store attachments in Emails or OneNote documents

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Launch

Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)Created Mon Dec 27Updated Tue Aug 0200d49ed5-4491-4271-a8db-650a4ef6f8c1windows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection_download:
        - Image|endswith:
              - '\curl.exe'
              - '\wget.exe'
        - CommandLine|contains:
              - 'Invoke-WebRequest'
              - 'iwr '
              - 'curl '
              - 'wget '
              - 'Start-BitsTransfer'
              - '.DownloadFile('
              - '.DownloadString('
    selection_domains:
        CommandLine|contains:
            - 'https://attachment.outlook.live.net/owa/'
            - 'https://onenoteonlinesync.onenote.com/onenoteonlinesync/'
    condition: all of selection_*