Potential OWASSRF Exploitation Attempt - Webserver

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 - Webserver
id: 181f49fa-0b21-4665-a98c-a57025ebb8c7
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
modified: 2023-01-02
tags:
    - attack.initial-access
    - attack.t1190
    - detection.emerging-threats
logsource:
    category: webserver
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_*
falsepositives:
    - Web vulnerability scanners
level: high

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

ed4f8069-1158-4388-9dd9-2f1048cfb374

Propose edits, view related rules, and engage with the community through comments.

Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

Community Discussion