Potential OWASSRF Exploitation Attempt - Proxy

SIGMA detection rule by Nasreddine Bencherchali (Nextron Systems) · NOASSERTION

Detects exploitation attempt of the OWASSRF variant targeting exchange servers It uses the OWA endpoint to access the powershell backend endpoint

title: Potential OWASSRF Exploitation Attempt - Proxy
id: 1ddf4596-1908-43c9-add2-1d2c2fcc4797
status: test
description: Detects exploitation attempt of the OWASSRF variant targeting exchange servers It uses the OWA endpoint to access the powershell backend endpoint
references:
    - https://www.crowdstrike.com/blog/owassrf-exploit-analysis-and-recommendations/
    - https://www.rapid7.com/blog/post/2022/12/21/cve-2022-41080-cve-2022-41082-rapid7-observed-exploitation-of-owassrf-in-exchange-for-rce/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-12-22
tags:
    - attack.initial-access
    - attack.t1190
    - detection.emerging-threats
logsource:
    category: proxy
detection:
    selection:
        cs-method: 'POST'
        sc-status: 200
        c-uri|contains|all:
            - '/owa/'
            - '/powershell'
        c-uri|contains:
            - '@'
            - '%40'
    filter_main_ua:
        c-useragent:
            - 'ClientInfo'
            - 'Microsoft WinRM Client'
            - 'Exchange BackEnd Probes'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Web vulnerability scanners
level: high

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f3f50ed5-848b-4402-b4a1-70a1e2b89951

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