Microsoft Exchange Web RCE Attempts via GET Requests Containing ECP/OWA and __VIEWSTATE

Alerts on web requests to Exchange ECP/OWA that include __VIEWSTATE= in the query.

FreeReviewedSigma · Critical · v5

Category: webserver
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2020-02-29
Updated: 2026-07-31

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags HTTP GET requests whose URI query contains both Exchange web paths (/ecp/ and /owa/) and includes the __VIEWSTATE parameter. Such activity can indicate an attempt to trigger Microsoft Exchange server functionality through web endpoints. Detection relies on webserver request telemetry capturing HTTP method and URI query parameters.

Reporting behind it

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Microsoft Exchange Web RCE Attempts via GET Requests Containing ECP/OWA and __VIEWSTATE

Pivot detection · T1190 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No 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.

microsoft-exchange-exploitation-web-requests-using-ecp-owa-and-viewstate-http-ge-fce2c2e2

title: Microsoft Exchange Web RCE Attempts via GET Requests Containing ECP/OWA and __VIEWSTATE
id: 04f815d0-3dbe-49f2-bcf5-be419cb1b457
status: test
description: This rule flags HTTP GET requests whose URI query contains both Exchange web paths (/ecp/ and /owa/) and includes the __VIEWSTATE parameter. Such activity can indicate an attempt to trigger Microsoft Exchange server functionality through web endpoints. Detection relies on webserver request telemetry capturing HTTP method and URI query parameters.
references:
  - https://www.trustedsec.com/blog/detecting-cve-20200688-remote-code-execution-vulnerability-on-microsoft-exchange-server/
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/Exploits/CVE-2020-0688/web_cve_2020_0688_msexchange.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2020-02-29
modified: 2023-01-02
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2020-0688
  - detection.emerging-threats
logsource:
  category: webserver
detection:
  selection1:
    cs-method: GET
    cs-uri-query|contains:
      - /ecp/
      - /owa/
  selection2:
    cs-uri-query|contains: __VIEWSTATE=
  condition: all of selection*
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: fce2c2e2-0fb5-41ab-a14c-5391e1fd70a5
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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