Suspicious PowerShell Mailbox Export to Share

Detects usage of the powerShell New-MailboxExportRequest Cmdlet to exports a mailbox to a remote or local share, as used in ProxyShell exploitations

Sigma rule (View on GitHub)

 1title: Suspicious PowerShell Mailbox Export to Share
 2id: 889719ef-dd62-43df-86c3-768fb08dc7c0
 3status: test
 4description: Detects usage of the powerShell New-MailboxExportRequest Cmdlet to exports a mailbox to a remote or local share, as used in ProxyShell exploitations
 5references:
 6    - https://youtu.be/5mqid-7zp8k?t=2481
 7    - https://blog.orange.tw/2021/08/proxylogon-a-new-attack-surface-on-ms-exchange-part-1.html
 8    - https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1
 9    - https://m365internals.com/2022/10/07/hunting-in-on-premises-exchange-server-logs/
10author: Florian Roth (Nextron Systems)
11date: 2021/08/07
12modified: 2022/10/26
13tags:
14    - attack.exfiltration
15logsource:
16    category: process_creation
17    product: windows
18detection:
19    selection:
20        CommandLine|contains|all:
21            - 'New-MailboxExportRequest'
22            - ' -Mailbox '
23            - ' -FilePath \\\\'
24    condition: selection
25fields:
26    - CommandLine
27    - ParentCommandLine
28falsepositives:
29    - Unknown
30level: critical

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