Suspicious PowerShell Mailbox Export to Share - PS

calendar Oct 17, 2023 · attack.exfiltration  ·
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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 - PS
 2id: 4a241dea-235b-4a7e-8d76-50d817b146c4
 3related:
 4    - id: 889719ef-dd62-43df-86c3-768fb08dc7c0
 5      type: derived
 6status: test
 7description: Detects usage of the powerShell New-MailboxExportRequest Cmdlet to exports a mailbox to a remote or local share, as used in ProxyShell exploitations
 8references:
 9    - https://youtu.be/5mqid-7zp8k?t=2481
10    - https://blog.orange.tw/2021/08/proxylogon-a-new-attack-surface-on-ms-exchange-part-1.html
11    - https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1
12    - https://m365internals.com/2022/10/07/hunting-in-on-premises-exchange-server-logs/
13author: Nasreddine Bencherchali (Nextron Systems)
14date: 2022/10/26
15tags:
16    - attack.exfiltration
17logsource:
18    product: windows
19    category: ps_script
20    definition: 'Requirements: Script Block Logging must be enabled'
21detection:
22    selection:
23        ScriptBlockText|contains|all:
24            - 'New-MailboxExportRequest'
25            - ' -Mailbox '
26            - ' -FilePath \\\\'
27    condition: selection
28fields:
29    - CommandLine
30    - ParentCommandLine
31falsepositives:
32    - Unknown
33level: critical

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