Emerging Threathightest

Potential OWASSRF Exploitation Attempt - Webserver

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

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Launch

Nasreddine Bencherchali (Nextron Systems)Created Thu Dec 22Updated Mon Jan 02181f49fa-0b21-4665-a98c-a57025ebb8c72022

Emerging Threat

Active Threat

Developed to detect an active or emerging threat. Prioritize investigation of any alerts and correlate with threat intelligence.

Log Source

Web Server Log

CategoryWeb Server Log← raw: webserver

HTTP access logs from web servers capturing request paths, methods, and status codes.

Detection Logic

detection:
    selection:
        cs-method: 'POST'
        sc-status: 200
        cs-uri-query|contains|all:
            - '/owa/'
            - '/powershell'
        cs-uri-query|contains:
            - '@'
            - '%40'
    filter_main_ua:
        cs-user-agent:
            - 'ClientInfo'
            - 'Microsoft WinRM Client'
            - 'Exchange BackEnd Probes'
    condition: selection and not 1 of filter_main_*