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MCMS v5.4.3 contains an arbitrary file upload vulnerability in its `ueditor` component, allowing attackers to upload malicious files and execute arbitrary code. The flaw occurs due to insufficient validation of file extensions and content in the upload handler. Attackers can bypass security checks by crafting a file (e.g., .php, .jsp) disguised as an allowed type (e.g., .jpg), then execute it on the server. This leads to remote code execution (RCE), compromising the system.
DailyCVE Form
Platform: MCMS
Version: 5.4.3
Vulnerability: Arbitrary File Upload
Severity: Critical
Date: Apr 21, 2025
What Undercode Say:
Exploitation:
1. Craft a malicious file (e.g., `shell.php.jpg`).
2. Bypass extension checks via null byte (`shell.php%00.jpg`).
3. Upload via `ueditor` endpoint (`/ueditor/upload`).
4. Access the file to trigger RCE.
Protection:
1. Disable `ueditor` if unused.
2. Implement strict file extension validation.
3. Use a whitelist for allowed file types.
4. Store uploads outside web root.
Detection Commands:
grep -r "ueditor/upload" /var/www/html/ find /uploads -name ".php" -o -name ".jsp"
Patch Code (PHP Example):
$allowed_ext = ['jpg', 'png', 'gif'];
$file_ext = strtolower(pathinfo($_FILES['file']['name'], PATHINFO_EXTENSION));
if (!in_array($file_ext, $allowed_ext)) {
die("Invalid file type.");
}
Log Analysis:
tail -f /var/log/apache2/access.log | grep "POST /ueditor/upload"
Mitigation Steps:
1. Update MCMS to the latest version.
2. Restrict upload permissions (`chmod 600 uploads/`).
3. Deploy a WAF to block malicious uploads.
Exploit Proof-of-Concept (PoC):
import requests
url = "http://target.com/ueditor/upload"
files = {'file': ('shell.php.jpg', open('shell.php', 'rb'))}
r = requests.post(url, files=files)
print(r.text)
Post-Exploit Checks:
SELECT FROM mcms_settings WHERE config LIKE '%upload%';
Network Protection:
location ~ /ueditor/upload {
deny all;
}
Signatures to Monitor:
– `Content-Disposition: form-data; name=”file”; filename=”.php”`
– `POST /ueditor/upload HTTP/1.1`
End of Report.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
