blue-team-tools/rules/web/web_exchange_proxyshell.yml

title: Exchange ProxyShell Pattern
id: 23eee45e-933b-49f9-ae1b-df706d2d52ef
status: experimental
description: Detects URL patterns that could be found in ProxyShell exploitation attempts against Exchange servers (failed and successful)
references:
    - https://youtu.be/5mqid-7zp8k?t=2231
    - https://blog.orange.tw/2021/08/proxylogon-a-new-attack-surface-on-ms-exchange-part-1.html
    - https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1
author: Florian Roth, Rich Warren
date: 2021/08/07
modified: 2021/08/08
tags:
    - attack.initial_access
logsource:
    category: webserver
detection:
    selection_auto:
        c-uri|contains: '/autodiscover.json'
    selection_uri:
        c-uri|contains:
            - '/powershell'
            - '/mapi/nspi'
            - '/EWS'
            - 'X-Rps-CAT'
    selection:
        sc-status: 401
    selection_poc:
        c-uri|contains: 
            # since we don't know how it will appear in the log files, we'll just use all versions
            - 'autodiscover.json?@'
            - 'autodiscover.json%3f@'
            - '%3f@foo.com'
            - 'Email=autodiscover/autodiscover.json'
            - 'json?@foo.com'
    condition: selection_auto and selection_uri or selection_poc 
falsepositives:
    - Unknown
level: medium