Detect iCagenda Unrestricted File Upload Exploitation (CVE-2026-48939) in Elastic Security
Detects exploitation attempts against CVE-2026-48939, an Unrestricted Upload of File with Dangerous Type vulnerability (CWE-434) in the iCagenda Joomla component. Attackers abuse insufficient file-type validation in iCagenda's upload handlers (event image/attachment upload endpoints) to upload web shells or other executable content, achieving remote code execution on the underlying web server. This CVE is listed in CISA KEV, indicating confirmed active exploitation and mandated remediation under BOD 26-04.
MITRE ATT&CK
- Tactic
- Initial Access Execution
Elastic Detection Query
any where event.dataset == "nginx.access" and
url.path : ("*com_icagenda*", "*icagenda*") and
http.request.method == "POST" and
url.path : ("*upload*", "*attachment*", "*image*") and
(url.path : ("*.php", "*.php5", "*.phtml", "*.phar", "*.pht", "*.asp", "*.aspx", "*.jsp") or http.response.status_code == 200)Elastic EQL rule to detect suspicious file upload activity targeting the iCagenda Joomla component consistent with CVE-2026-48939.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate iCagenda event image uploads by authenticated staff
- Scheduled security scans
- Load balancer health checks hitting similar paths
Other platforms for CVE-2026-48939
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate malicious PHP upload to iCagenda endpoint
Expected signal: Web server access log entry showing POST to com_icagenda upload path with HTTP 200 response, followed by a new file creation event in the media/com_icagenda upload directory
- Test 2Verify uploaded shell executability
Expected signal: GET request to the uploaded PHP file logged, followed by php-fpm/apache2 spawning a child process (id) consistent with web shell command execution
- Test 3Windows IIS-hosted Joomla upload simulation
Expected signal: W3C IIS log entry recording POST to com_icagenda upload endpoint with dangerous .aspx extension and 200 status
References (4)
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