Detect iCagenda Unrestricted File Upload Exploitation (CVE-2026-48939) in Microsoft Sentinel
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
KQL Detection Query
let SuspiciousExt = dynamic([".php",".php5",".phtml",".phar",".pht",".asp",".aspx",".jsp"]);
W3CIISLog
| where csUriStem has_any ("/components/com_icagenda/", "/media/com_icagenda/", "icagenda")
| where csMethod == "POST"
| where csUriStem has_any ("upload", "attachment", "image")
| extend FileExt = tostring(extract(@"(\.[A-Za-z0-9]+)$", 1, csUriStem))
| where FileExt in (SuspiciousExt) or scStatus == 200
| project TimeGenerated, cIP, csMethod, csUriStem, csUserAgent, scStatus
| order by TimeGenerated descDetects POST requests to iCagenda upload endpoints on Joomla sites followed by requests to files with dangerous extensions, indicating exploitation of CVE-2026-48939.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate administrators uploading permitted image types via iCagenda backend
- Vulnerability scanners performing authorized testing
- Misconfigured monitoring tools polling the same URI patterns
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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