Certificate Request Export to Exchange Webserver

 1title: Certificate Request Export to Exchange Webserver
 2id: b7bc7038-638b-4ffd-880c-292c692209ef
 3status: test
 4description: Detects a write of an Exchange CSR to an untypical directory or with aspx name suffix which can be used to place a webshell
 5references:
 6    - https://twitter.com/GossiTheDog/status/1429175908905127938
 7author: Max Altgelt (Nextron Systems)
 8date: 2021-08-23
 9modified: 2023-01-23
10tags:
11    - attack.persistence
12    - attack.t1505.003
13logsource:
14    service: msexchange-management
15    product: windows
16detection:
17    keywords_export_command:
18        '|all':
19            - 'New-ExchangeCertificate'
20            - ' -GenerateRequest'
21            - ' -BinaryEncoded'
22            - ' -RequestFile'
23    keywords_export_params:
24        - '\\\\localhost\\C$'
25        - '\\\\127.0.0.1\\C$'
26        - 'C:\\inetpub'
27        - '.aspx'
28    condition: keywords_export_command and keywords_export_params
29falsepositives:
30    - Unlikely
31level: critical