CVE-2025-57795

Executive Summary

CVE-2025-57795 is an authenticated remote file download vulnerability in Explorance Blue versions prior to 8.14.13. The flaw resides in a web service component, allowing an authenticated attacker to download arbitrary files from the server. In default configurations, this can be chained to achieve remote code execution (RCE). No public proof-of-concept (PoC) or exploit code is currently available, and the EPSS score is 0.0%, indicating low exploitation activity. The vendor has not released a public advisory, but the fix is included in version 8.14.13.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary enterprise application (Explorance Blue) and is not part of a public package registry.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder. Based on the description (authenticated remote file download leading to RCE), a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): Low (L) – requires authentication
• User Interaction (UI): None (N)
• Scope (S): Unchanged (U)
• Confidentiality (C): High (H)
• Integrity (I): High (H)
• Availability (A): High (H)

Estimated CVSS Score: 8.8 (High)

Threat Level: High – due to the potential for RCE and the fact that the vulnerability is in a web service component accessible over the network.

Deep Dive & Mechanics

The vulnerability exists in a web service component of Explorance Blue. The component fails to properly validate user-supplied file paths, allowing an authenticated attacker to download arbitrary files from the server's filesystem. This is a classic path traversal or arbitrary file read vulnerability (CWE-552: Files or Directories Accessible to External Parties).

Attack Flow:

1. Authentication: The attacker must first authenticate to the Explorance Blue application (e.g., with valid user credentials).
2. Exploitation: The attacker sends a crafted HTTP request to the vulnerable web service endpoint, specifying a file path outside the intended directory (e.g., using ../ sequences).
3. File Download: The server responds with the contents of the requested file, which could include sensitive configuration files, source code, or credentials.
4. RCE Chaining: In default configurations, the attacker can download files that contain secrets (e.g., database credentials, API keys) or configuration files that allow further exploitation. For example, downloading a configuration file that contains a secret key used for session signing could allow session hijacking, or downloading a database configuration file could enable SQL injection or direct database access. Ultimately, this can lead to remote code execution.

Root Cause: The web service component does not sanitize or validate the file parameter, allowing directory traversal.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

@app.route('/download')
def download_file():
    filename = request.args.get('file')
    # No validation of filename
    return send_file(filename)

Patched Code (Conceptual):

import os

@app.route('/download')
def download_file():
    filename = request.args.get('file')
    # Validate that the file is within the allowed directory
    allowed_dir = '/var/www/blue/uploads'
    full_path = os.path.normpath(os.path.join(allowed_dir, filename))
    if not full_path.startswith(allowed_dir):
        return "Access denied", 403
    return send_file(full_path)

The patched version uses os.path.normpath and checks that the resolved path starts with the allowed directory, preventing directory traversal.

Exploitation & Lab Setup

Red Team (Attacker)

Lab Setup:

1. Install Explorance Blue version 8.14.12 (or earlier) in a controlled environment.
2. Create a user account with valid credentials.
3. Identify the vulnerable web service endpoint (e.g., /download?file=).

Exploitation Steps:

1. Authenticate to the application and obtain a session cookie.
2. Send a request to download a sensitive file:

   GET /download?file=../../etc/passwd HTTP/1.1
   Host: target.example.com
   Cookie: session=valid_session_cookie
   

3. The server responds with the contents of /etc/passwd.
4. To achieve RCE, download configuration files (e.g., ../../app/config/database.yml) to extract database credentials, then use those credentials to execute SQL commands or upload a web shell.

Example cURL command:

curl -b "session=valid_session_cookie" "http://target.example.com/download?file=../../etc/passwd"

Blue Team (Defender)

Detection:

• Monitor for HTTP requests containing ../ or %2e%2e/ in the file parameter.
• Alert on unusual file download requests (e.g., downloading /etc/passwd, /proc/self/environ, or application configuration files).
• Use web application firewalls (WAF) to block path traversal patterns.

Mitigation:

• Immediately upgrade to Explorance Blue version 8.14.13 or later.
• If upgrade is not possible, implement a virtual patch by adding WAF rules to block directory traversal attempts.
• Restrict file download functionality to only allow files from a specific directory.
• Implement strict input validation and output encoding.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with file parameter containing ../ or %2e%2e/
  • Unusual file paths in download requests (e.g., /etc/passwd, /windows/win.ini)
  • Multiple failed authentication attempts followed by file download requests (if brute-forcing credentials)
• File System IOCs:
  • Unexpected files in the web root (e.g., web shells)
  • Modified configuration files
• Log IOCs:
  • Web server logs showing 200 responses to requests with path traversal patterns
  • Application logs showing access to files outside the intended directory

Detection Engineering

YARA Rule

rule CVE_2025_57795_Explorance_Blue_Path_Traversal {
    meta:
        description = "Detects path traversal attempts in HTTP requests targeting Explorance Blue"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-57795"
    strings:
        $path_traversal = /\.\.(\/|%2f|\\|%5c)/ nocase
        $file_param = "file=" nocase
    condition:
        $file_param and $path_traversal
}

Sigma Rule

title: CVE-2025-57795 - Explorance Blue Path Traversal
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects path traversal attempts in HTTP requests to Explorance Blue
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: 
            - 'file=../'
            - 'file=%2e%2e/'
            - 'file=..%2f'
            - 'file=%2e%2e%2f'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in some configurations (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-57795 - Explorance Blue Path Traversal Attempt"; flow:to_server,established; content:"file="; nocase; content:"../"; within:100; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Upgrade Explorance Blue to version 8.14.13 or later. This is the only official fix.
2. Virtual Patching: If upgrade is not possible, deploy a WAF rule to block requests containing ../ or %2e%2e/ in the file parameter.
3. Access Control: Restrict network access to the Explorance Blue web interface to trusted IP addresses only.

Long-Term Measures:

• Implement a secure code review process for all web service components.
• Use input validation libraries that automatically sanitize file paths.
• Apply the principle of least privilege to the application's filesystem access.
• Regularly update and patch all software components.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.