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

Sigma rule (View on GitHub)

 1title: Suspicious Download from Office Domain
 2id: 00d49ed5-4491-4271-a8db-650a4ef6f8c1
 3status: test
 4description: Detects suspicious ways to download files from Microsoft domains that are used to store attachments in Emails or OneNote documents
 5references:
 6    - https://twitter.com/an0n_r0/status/1474698356635193346?s=12
 7    - https://twitter.com/mrd0x/status/1475085452784844803?s=12
 8author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
 9date: 2021-12-27
10modified: 2022-08-02
11tags:
12    - attack.command-and-control
13    - attack.t1105
14    - attack.t1608
15logsource:
16    product: windows
17    category: process_creation
18detection:
19    selection_download:
20        - Image|endswith:
21              - '\curl.exe'
22              - '\wget.exe'
23        - CommandLine|contains:
24              - 'Invoke-WebRequest'
25              - 'iwr '
26              - 'curl '
27              - 'wget '
28              - 'Start-BitsTransfer'
29              - '.DownloadFile('
30              - '.DownloadString('
31    selection_domains:
32        CommandLine|contains:
33            - 'https://attachment.outlook.live.net/owa/'
34            - 'https://onenoteonlinesync.onenote.com/onenoteonlinesync/'
35    condition: all of selection_*
36falsepositives:
37    - Scripts or tools that download attachments from these domains (OneNote, Outlook 365)
38level: high

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