CVE-2024-50620

Executive Summary

CVE-2024-50620 is a critical unrestricted file upload vulnerability affecting CIPPlanner CIPAce versions prior to 9.17. The flaw exists in two components: the rich text editor (during image insertion) and the document management page (during file uploads). An authenticated user can upload executable files (e.g., scripts, binaries) that, if stored in a directory with execute permissions or outside a shared directory, can be executed on the server. This can lead to remote code execution, privilege escalation, or full system compromise. No public proof-of-concept or exploit code is available at this time, but the risk is high due to the ease of exploitation by an authorized user.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It affects a proprietary enterprise application (CIPPlanner CIPAce). Organizations should verify the integrity of their CIPAce installation and ensure no unauthorized modifications have been made.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0 in the NVD data, likely due to incomplete scoring. Based on the description, a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) – the upload is performed over the network.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): Low (L) – an authenticated user is needed.
• User Interaction (UI): None (N) – no user interaction required beyond the attacker.
• Scope (S): Unchanged (U) – the vulnerable component is the application itself.
• Confidentiality (C): High (H) – arbitrary code execution can lead to data exfiltration.
• Integrity (I): High (H) – uploaded files can modify system state.
• Availability (A): High (H) – code execution can disrupt services.

Estimated CVSS Score: 8.8 (High)

Threat Level: High – authenticated users can achieve remote code execution with minimal effort.

Deep Dive & Mechanics

The vulnerability stems from insufficient validation of file types during upload in two distinct features:

1. Rich Text Editor (Image Insertion): When an authenticated user inserts an image into a rich text editor, the application does not verify that the uploaded file is a valid image (e.g., checking MIME type, magic bytes, or extension). An attacker can upload a PHP script, JSP file, or other executable disguised as an image.
2. Document Management Page: Similarly, the document management component allows file uploads without restricting dangerous file types (e.g., .exe, .sh, .war). The application only checks for file existence or size, not content.

The critical condition for exploitation is that the uploaded file must be stored in a directory that has execute permissions or is not a shared directory (which typically disables execution). If the storage directory allows execution (e.g., a web-accessible directory with execute permissions), the attacker can directly access the uploaded file via a URL and trigger its execution.

Attack Flow:

1. Authenticate to CIPPlanner CIPAce.
2. Navigate to a page with the rich text editor or document management.
3. Upload a malicious file (e.g., shell.php) with a valid image extension (e.g., shell.php.jpg) or directly as a document.
4. If the file is stored in a web-accessible directory with execute permissions, access the file via HTTP (e.g., https://target/cipace/uploads/shell.php.jpg).
5. The server executes the file, granting the attacker code execution.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-9.17): The application likely uses a simple file extension whitelist or no validation at all. Example pseudocode:

// Vulnerable upload handler
if (isset($_FILES['file'])) {
    $target_dir = "uploads/";
    $target_file = $target_dir . basename($_FILES["file"]["name"]);
    move_uploaded_file($_FILES["file"]["tmp_name"], $target_file);
}

No check on file type, MIME, or content.

Patched Code (9.17+): The patched version should implement strict validation:

// Patched upload handler
$allowed_types = ['image/jpeg', 'image/png', 'image/gif', 'application/pdf'];
$finfo = finfo_open(FILEINFO_MIME_TYPE);
$mime_type = finfo_file($finfo, $_FILES["file"]["tmp_name"]);
finfo_close($finfo);

if (!in_array($mime_type, $allowed_types)) {
    die("Invalid file type.");
}
// Also check file extension and ensure no executable bits
$extension = strtolower(pathinfo($_FILES["file"]["name"], PATHINFO_EXTENSION));
$allowed_ext = ['jpg', 'jpeg', 'png', 'gif', 'pdf'];
if (!in_array($extension, $allowed_ext)) {
    die("Invalid extension.");
}
// Store in a non-executable directory
$target_dir = "uploads/";
$target_file = $target_dir . uniqid() . "." . $extension;
move_uploaded_file($_FILES["file"]["tmp_name"], $target_file);

Exploitation & Lab Setup

Red Team (Attacker)

Lab Setup:

• Target: CIPPlanner CIPAce version 9.16 (or earlier) running on a Windows/Linux server with a web server (IIS/Apache).
• Attacker: Kali Linux with a web shell (e.g., p0wny-shell or custom PHP script).

Exploitation Steps:

1. Obtain valid credentials for a low-privileged user.
2. Log in to the CIPAce web interface.
3. Navigate to a page with the rich text editor (e.g., creating a new document).
4. Click "Insert Image" and upload a file named shell.php.jpg containing:

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

5. Note the upload path (e.g., /uploads/shell.php.jpg).
6. Access the file via browser: https://target/cipace/uploads/shell.php.jpg?cmd=whoami
7. If the server executes PHP, the command runs. If not, try other extensions (e.g., .asp, .jsp, .war).

Alternative via Document Management:

1. Go to Document Management.
2. Upload a file named exploit.exe or exploit.sh.
3. If the directory has execute permissions, trigger execution via direct access or social engineering.

Blue Team (Defender)

Detection Steps:

• Monitor file upload logs for unusual file extensions (e.g., .php, .asp, .exe, .sh).
• Check for files with double extensions (e.g., image.php.jpg).
• Verify that upload directories have execute permissions disabled (e.g., chmod -x on Linux, or disable script execution in IIS).
• Use file integrity monitoring to detect new files in upload directories.

Hunting Query (Splunk):

index=web_logs source="/var/log/apache2/access.log"
| search uri_path="/uploads/*" AND (uri_path="*.php*" OR uri_path="*.asp*" OR uri_path="*.exe*")
| stats count by src_ip, uri_path, status

Indicators of Compromise (IOCs)

• File Hashes (Example):
  • shell.php.jpg: MD5 d41d8cd98f00b204e9800998ecf8427e (empty file, adjust for actual payload)
• Network Indicators:
  • HTTP requests to /uploads/ with suspicious file extensions.
  • Outbound connections from the server to attacker-controlled IPs (if reverse shell).
• File System Indicators:
  • Unexpected files in upload directories with executable extensions.
  • Files with double extensions (e.g., image.php.jpg).
• Log Indicators:
  • Web server logs showing 200 responses for uploaded executable files.
  • Application logs showing file uploads from non-admin users.

Detection Engineering

YARA Rule

rule CVE_2024_50620_Uploaded_Executable {
    meta:
        description = "Detects uploaded executable files in CIPPlanner CIPAce upload directories"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2024-50620"
    strings:
        $php_tag = "<?php"
        $asp_tag = "<%"
        $jsp_tag = "<%"
        $exe_magic = { 4D 5A }  // MZ header for PE files
        $elf_magic = { 7F 45 4C 46 }  // ELF header
    condition:
        any of ($php_tag, $asp_tag, $jsp_tag) or $exe_magic or $elf_magic
}

Sigma Rule

title: CVE-2024-50620 - Unrestricted File Upload in CIPPlanner CIPAce
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects upload of executable files to CIPPlanner CIPAce
author: Valters IT
date: 2025/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/uploads/*'
        cs-uri-extension:
            - '.php'
            - '.asp'
            - '.exe'
            - '.sh'
            - '.jsp'
    condition: selection
falsepositives:
    - Legitimate file uploads if application requires executable files (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-50620 - Unrestricted File Upload in CIPPlanner CIPAce"; flow:to_server,established; content:"POST"; http_method; content:"/uploads/"; http_uri; pcre:"/\.(php|asp|exe|sh|jsp)/iU"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade to CIPPlanner CIPAce version 9.17 or later.
2. If upgrade is not possible, restrict file uploads to only trusted users and disable execute permissions on upload directories.
3. Implement a web application firewall (WAF) rule to block uploads of executable file extensions.

Long-term Fixes:

• Enforce strict file type validation using MIME type and magic bytes.
• Store uploaded files in a directory with no execute permissions (e.g., chmod 644 on Linux, or disable script execution in IIS).
• Rename uploaded files to random names without user-controlled extensions.
• Conduct regular security audits of file upload functionality.

Workaround:

• Disable the rich text editor and document management features if not essential.
• Use a reverse proxy to inspect and block malicious uploads.

Valters IT
Securing Your Digital Frontier