Sitecore Pre-Auth RCE (CVE-2021-42237) exploitation attempts via Report.ashx POST

Alerts on successful HTTP POST traffic targeting Sitecore Reporting Report.ashx associated with CVE-2021-42237.

FreeReviewedSigma · High · v5

Category: webserver
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-11-17
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 requests that return a 200 response where the request is a POST with a query containing /sitecore/shell/ClientBin/Reporting/Report.ashx. This matters because successful pre-auth RCE exploitation attempts against Sitecore could enable remote code execution without authentication. The detection relies on webserver HTTP telemetry including request method, URI query content, and HTTP status codes.

Reporting behind it

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Sitecore Pre-Auth RCE (CVE-2021-42237) exploitation attempts via Report.ashx POST

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.

sitecore-pre-auth-rce-exploitation-attempts-via-report-ashx-cve-2021-42237-on-we-20c6ed1c

title: Sitecore Pre-Auth RCE (CVE-2021-42237) exploitation attempts via Report.ashx POST
id: 868059d5-b343-4653-9b41-5f2df4ef6f85
status: test
description: This rule flags HTTP requests that return a 200 response where the request is a POST with a query containing /sitecore/shell/ClientBin/Reporting/Report.ashx. This matters because successful pre-auth RCE exploitation attempts against Sitecore could enable remote code execution without authentication. The detection relies on webserver HTTP telemetry including request method, URI query content, and HTTP status codes.
references:
  - https://blog.assetnote.io/2021/11/02/sitecore-rce/
  - https://support.sitecore.com/kb?id=kb_article_view&sysparm_article=KB1000776
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2021/Exploits/CVE-2021-42237/web_cve_2021_42237_sitecore_report_ashx.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2021-11-17
modified: 2023-01-02
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2021-42237
  - detection.emerging-threats
logsource:
  category: webserver
detection:
  selection:
    cs-method: POST
    cs-uri-query|contains: /sitecore/shell/ClientBin/Reporting/Report.ashx
    sc-status: 200
  condition: selection
falsepositives:
  - Vulnerability Scanning
level: high
license: DRL-1.1
related:
  - id: 20c6ed1c-f7f0-4ea3-aa65-4f198e6acb0f
    type: derived

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