CVE-2025-14521

Executive Summary

CVE-2025-14521 is a path traversal vulnerability discovered in the baowzh hfly application, a rolling-release project. The flaw resides in the /admin/index.php/datafile/download endpoint, where the filename argument is not properly sanitized, allowing an attacker to read arbitrary files from the server filesystem. The vulnerability is remotely exploitable without authentication, and a public proof-of-concept (PoC) exists. The vendor has not responded to disclosure attempts, and no official patch is available. The CVSS score is 4.3 (Medium), reflecting the low confidentiality impact but ease of exploitation.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component remains the same.
• Confidentiality (C): Low (L) – Limited file read capability.
• Integrity (I): None (N) – No file modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The vulnerability is easy to exploit and has a public PoC, but the impact is limited to reading files (e.g., configuration files, source code). It could be used as a stepping stone for more severe attacks if sensitive data (e.g., credentials) is exposed.

Deep Dive & Mechanics

The vulnerability is a classic path traversal (directory traversal) in the download function of the datafile module. The application likely constructs a file path by concatenating a base directory with the user-supplied filename parameter without proper validation. An attacker can inject ../ sequences to escape the intended directory and read arbitrary files.

Example vulnerable code (conceptual PHP):

$filename = $_GET['filename'];
$filepath = '/var/www/hfly/data/' . $filename;
if (file_exists($filepath)) {
    header('Content-Type: application/octet-stream');
    readfile($filepath);
}

The attacker can request:

/admin/index.php/datafile/download?filename=../../../../etc/passwd

This would read /etc/passwd from the server.

Vulnerable vs. Patched Code

Vulnerable Code (conceptual):

$filename = $_GET['filename'];
$filepath = '/var/www/hfly/data/' . $filename;
if (file_exists($filepath)) {
    readfile($filepath);
}

Patched Code (conceptual):

$filename = basename($_GET['filename']); // Strip path components
$filepath = '/var/www/hfly/data/' . $filename;
if (file_exists($filepath) && strpos(realpath($filepath), '/var/www/hfly/data/') === 0) {
    readfile($filepath);
}

The patch uses basename() to remove directory traversal sequences and realpath() to verify the resolved path stays within the allowed directory.

Exploitation & Lab Setup

Red Team (Attack Simulation)

1. Setup: Deploy a vulnerable instance of baowzh hfly (commit 638ff9abe9078bc977c132b37acbe1900b63491c) in a Docker container.
2. Exploit: Use curl to exploit the path traversal:

   curl "http://target.com/admin/index.php/datafile/download?filename=../../../../etc/passwd"
   

3. Advanced: Read application configuration files to extract database credentials:

   curl "http://target.com/admin/index.php/datafile/download?filename=../../../../var/www/hfly/config.php"
   

Blue Team (Defense & Detection)

1. Monitor: Look for HTTP requests to /admin/index.php/datafile/download with filename parameters containing ../ or ..\.
2. Block: Implement WAF rules to block path traversal patterns.
3. Harden: Ensure the application runs with minimal file system permissions.

Indicators of Compromise (IOCs)

• Network: HTTP GET requests to /admin/index.php/datafile/download with filename containing ../.
• File System: Unexpected access to /etc/passwd, /etc/shadow, or application configuration files.
• Logs: Web server logs showing 404 or 200 responses for path traversal attempts.

Detection Engineering

YARA Rule

rule CVE_2025_14521_PathTraversal {
    meta:
        description = "Detects path traversal attempts targeting CVE-2025-14521"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-14521"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $endpoint = "/admin/index.php/datafile/download"
    condition:
        $endpoint and any of ($traversal*)
}

Sigma Rule

title: CVE-2025-14521 Path Traversal Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects path traversal attempts against baowzh hfly download endpoint
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem: '/admin/index.php/datafile/download'
        cs-uri-query|contains: 'filename='
    condition: selection and (cs-uri-query|contains: '../' or cs-uri-query|contains: '..\\')
falsepositives:
    - Legitimate use of relative paths (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-14521 Path Traversal Attempt"; flow:to_server,established; content:"/admin/index.php/datafile/download"; http_uri; content:"filename="; http_uri; pcre:"/filename=[^&]*\.\.\//i"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: If possible, disable the /admin/index.php/datafile/download endpoint or restrict access via .htaccess or firewall rules.
2. Code Fix: Implement input validation using basename() and realpath() as shown in the patched code example.
3. WAF: Deploy a Web Application Firewall rule to block ../ sequences in the filename parameter.
4. Monitoring: Enable detailed logging and alert on path traversal patterns.
5. Vendor Contact: Since the vendor is unresponsive, consider forking the project and applying the fix yourself.

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