Detects OWASSRF Proxy Exploitation Attempt via OWA to PowerShell Backend
Identifies proxy POSTs that return 200 and request both /owa/mastermailbox and /powershell, indicating potential OWASSRF exploitation.
- Category
- proxy
- Author
- Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2022-12-22
- Updated
- 2026-07-31
ATT&CK techniques
Initial AccessRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags HTTP POST requests that use the OWA master mailbox path and target the /powershell backend in a way consistent with an OWASSRF exploitation attempt. It matters because attackers can leverage the proxy behavior of Exchange OWA to reach PowerShell endpoints. The detection relies on proxy telemetry fields such as client user agent, request method, response status, and the requested URI path segments.
Reporting behind it
- crowdstrike.comhttps://www.crowdstrike.com/blog/owassrf-exploit-analysis-and-recommendations/
- rapid7.comhttps://www.rapid7.com/blog/post/2022/12/21/cve-2022-41080-cve-2022-41082-rapid7-observed-exploitation-of-owassrf-in-exchange-for-rce/
- twitter.comhttps://twitter.com/purp1ew0lf/status/1602989967776808961?s=12&t=OkZJl_ViICeiftVEsohRyw
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2022/Exploits/CVE-2022-41082/proxy_cve_2022_36804_exchange_owassrf_poc_exploitation.yml
Changelog
v5- v5Candidate ingested via manual entry.2026-07-31
- v4Candidate ingested via manual entry.2026-07-31
- v3Candidate ingested via manual entry.2026-07-31
- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: Detects OWASSRF Proxy Exploitation Attempt via OWA to PowerShell Backend
id: 2f5df738-7ed1-469d-bf27-269e00b142cb
status: test
description: This rule flags HTTP POST requests that use the OWA master mailbox path and target the /powershell backend in a way consistent with an OWASSRF exploitation attempt. It matters because attackers can leverage the proxy behavior of Exchange OWA to reach PowerShell endpoints. The detection relies on proxy telemetry fields such as client user agent, request method, response status, and the requested URI path segments.
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/
- https://twitter.com/purp1ew0lf/status/1602989967776808961?s=12&t=OkZJl_ViICeiftVEsohRyw
- https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2022/Exploits/CVE-2022-41082/proxy_cve_2022_36804_exchange_owassrf_poc_exploitation.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-12-22
tags:
- attack.initial-access
- attack.t1190
- detection.emerging-threats
logsource:
category: proxy
detection:
selection:
c-useragent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.5195.54 Safari/537.36
cs-method: POST
sc-status: 200
c-uri|contains|all:
- /owa/mastermailbox
- /powershell
condition: selection
falsepositives:
- Unlikely
level: critical
license: DRL-1.1
related:
- id: fdd7e904-7304-4616-a46a-e32f917c4be4
type: derived