CVE-2025-32057

Executive Summary

CVE-2025-32057 exposes a critical flaw in the Infotainment ECU of the Nissan Leaf ZE1 (2020 model), manufactured by Bosch. The vulnerability stems from the Redbend over-the-air (OTA) update service failing to validate the server’s root certificate. By default, the underlying SSL engine is configured to trust any certificate, including self-signed ones. This allows an attacker on the network path to impersonate the legitimate Redbend backend server, intercept and modify OTA updates, or inject malicious firmware.

The CVSS score of 6.5 (Medium) reflects the high impact on integrity and confidentiality, but the attack complexity is elevated due to the need for network proximity or man-in-the-middle (MITM) positioning. No public exploit code or proof-of-concept (PoC) is currently available, and no patch has been released by Bosch or Nissan. The EPSS score of 0.0% indicates low exploitation activity in the wild, but the risk remains significant for targeted attacks against electric vehicle (EV) fleets.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware supply chain issue involving Bosch’s Infotainment ECU and the Redbend OTA service. The default SSL configuration was inherited from the Redbend software development kit (SDK) and was not hardened by Bosch or Nissan during integration.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network – The attacker can exploit this remotely, but must be on the same network segment or able to intercept traffic.
• Attack Complexity (AC): High – Requires a MITM position, ARP spoofing, or DNS poisoning to intercept the OTA connection.
• Privileges Required (PR): None – No authentication needed.
• User Interaction (UI): None – The vehicle automatically checks for updates.
• Scope (S): Unchanged – The vulnerable component is the Infotainment ECU itself.
• Confidentiality (C): High – An attacker can read OTA update payloads and potentially extract sensitive data.
• Integrity (I): High – An attacker can modify firmware updates, injecting malicious code.
• Availability (A): None – The attack does not directly affect availability.

Threat Level: Medium-High. While the CVSS score is 6.5, the real-world impact on vehicle safety and fleet operations elevates the risk. A successful attack could lead to remote code execution (RCE) on the ECU, persistent backdoors, or even physical manipulation of vehicle functions (e.g., disabling brakes or steering if the ECU controls such systems).

Deep Dive & Mechanics

The Redbend OTA service is designed to securely deliver firmware updates to the Infotainment ECU. The communication uses HTTPS to encrypt the channel. However, the SSL/TLS implementation is configured with a default trust store that does not verify the server’s root certificate against a known Certificate Authority (CA). This means the client (the ECU) will accept any certificate presented by the server, including a self-signed one.

Attack Flow:

1. Reconnaissance: The attacker identifies a Nissan Leaf ZE1 on the same Wi-Fi network or cellular connection (e.g., via a rogue cell tower or compromised hotspot).
2. MITM Setup: The attacker performs ARP spoofing, DNS poisoning, or sets up a rogue access point to intercept traffic between the vehicle and the legitimate Redbend server (e.g., ota.redbend.com).
3. Certificate Impersonation: The attacker generates a self-signed certificate for the Redbend server’s domain and presents it to the ECU during the TLS handshake.
4. Update Interception: The ECU accepts the fake certificate and establishes an encrypted session with the attacker’s server.
5. Payload Manipulation: The attacker can now:
   • Read the legitimate update payload (confidentiality breach).
   • Replace the payload with a malicious firmware image (integrity breach).
   • Inject a backdoor or ransomware into the ECU.
6. Persistence: The malicious firmware is flashed to the ECU, giving the attacker persistent access.

Root Cause: The Redbend SDK’s default SSL configuration likely uses a TrustManager that trusts all certificates (e.g., TrustAllCertificates in Java or SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE) in OpenSSL). This is a classic CWE-295 (Improper Certificate Validation) vulnerability.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual – Redbend SDK default):

// Java example using HttpsURLConnection
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
// Default TrustManager that trusts all certificates
TrustManager[] trustAllCerts = new TrustManager[] {
    new X509TrustManager() {
        public java.security.cert.X509Certificate[] getAcceptedIssuers() { return null; }
        public void checkClientTrusted(X509Certificate[] certs, String authType) { }
        public void checkServerTrusted(X509Certificate[] certs, String authType) { }
    }
};
SSLContext sc = SSLContext.getInstance("TLS");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
conn.setSSLSocketFactory(sc.getSocketFactory());

Patched Code (Expected Fix):

// Proper certificate validation
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
// Use default TrustManager that validates against system CA store
SSLContext sc = SSLContext.getInstance("TLS");
sc.init(null, null, new java.security.SecureRandom()); // null = default TrustManager
conn.setSSLSocketFactory(sc.getSocketFactory());

Key Difference: The patched version uses the default TrustManager (which validates certificates against the system’s CA store) instead of a custom TrustManager that accepts all certificates. The fix also requires pinning the Redbend server’s certificate or using a proper CA-signed certificate.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A Nissan Leaf ZE1 (2020) with the vulnerable Infotainment ECU.
• Network access to the vehicle (same Wi-Fi or cellular MITM).
• A machine running Kali Linux with bettercap, mitmproxy, or responder.

Step-by-Step Exploitation:

1. Network Reconnaissance:

   sudo bettercap -eval "set arp.spoof.targets 192.168.1.100; arp.spoof on; net.sniff on"
   

   Replace 192.168.1.100 with the vehicle’s IP.

2. DNS Spoofing (Redirect Redbend domain):

   sudo bettercap -eval "set dns.spoof.domains ota.redbend.com; dns.spoof on"
   

3. Set Up Malicious HTTPS Server:

   # Generate self-signed certificate
   openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes -subj "/CN=ota.redbend.com"
   
   # Start mitmproxy with custom certificate
   mitmproxy --listen-port 443 --ssl-insecure --cert=cert.pem
   

4. Intercept and Modify Update:

   • Use mitmproxy to capture the update request.
   • Replace the firmware binary with a malicious one (e.g., a backdoor that opens a reverse shell).
   • Forward the modified response to the vehicle.

5. Trigger Update:

   • The vehicle will automatically check for updates (or the attacker can simulate a server-initiated update).
   • The ECU accepts the fake certificate and installs the malicious firmware.

Expected Outcome: The attacker gains persistent code execution on the Infotainment ECU.

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor for unexpected TLS certificates on the network (e.g., self-signed certs for known OTA domains).
• Use network intrusion detection systems (NIDS) to flag anomalous HTTPS connections to Redbend servers.
• Implement certificate pinning in the ECU firmware (requires vendor patch).

Lab Setup for Testing:

• Use a test Nissan Leaf ZE1 ECU (or emulator) in an isolated network.
• Deploy a rogue Redbend server with a self-signed certificate.
• Monitor logs for TLS handshake failures or unexpected certificate acceptance.

Honeypot:

• Set up a fake Redbend server that logs all connection attempts and certificate details.

Indicators of Compromise (IOCs)

Detection Engineering

YARA Rule

rule CVE_2025_32057_Redbend_SSL_Bypass {
    meta:
        description = "Detects vulnerable Redbend OTA client with disabled certificate validation"
        author = "Valters IT"
        date = "2025-04-17"
        cve = "CVE-2025-32057"
    strings:
        $s1 = "TrustAllCertificates" nocase
        $s2 = "SSL_VERIFY_NONE" nocase
        $s3 = "checkServerTrusted" nocase
        $s4 = "getAcceptedIssuers" nocase
        $s5 = "X509TrustManager" nocase
    condition:
        any of ($s*) and filesize < 10MB
}

Sigma Rule

title: CVE-2025-32057 - Redbend OTA Certificate Validation Bypass
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects network traffic indicating a Redbend OTA client accepting self-signed certificates
author: Valters IT
date: 2025-04-17
logsource:
    category: network_connection
    product: zeek
detection:
    selection:
        server_name: "ota.redbend.com"
        certificate_issuer: "CN=*"  # Self-signed or unknown issuer
        validation_status: "self_signed"
    condition: selection
falsepositives:
    - Legitimate testing environments
level: high
tags:
    - attack.t1190
    - cve.2025.32057

Suricata Rule

alert tls $HOME_NET any -> $EXTERNAL_NET 443 (
    msg:"CVE-2025-32057 - Redbend OTA Self-Signed Certificate Detected";
    flow:to_server,established;
    tls.cert_issuer; content:"CN="; nocase;
    tls.cert_subject; content:"ota.redbend.com"; nocase;
    tls.cert_notbefore; content:"2025"; nocase;
    sid:10000001;
    rev:1;
    reference:cve,2025-32057;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions (Workaround):

1. Network Segmentation: Isolate the Infotainment ECU from the internet and critical vehicle systems (CAN bus). Use a firewall to restrict outbound connections to only known Redbend IPs.
2. Certificate Pinning: Manually pin the Redbend server’s certificate in the ECU’s trust store (requires firmware modification – consult Bosch/Nissan).
3. Disable OTA Updates: Temporarily disable automatic OTA updates until a patch is available. This can be done via the vehicle’s settings menu or by blocking the update server at the network level.

Vendor Patch (Expected):

• Bosch and Nissan must release a firmware update that:
  • Enables proper certificate validation (CWE-295 fix).
  • Implements certificate pinning for the Redbend server.
  • Adds integrity checks for update payloads (e.g., digital signatures).

Long-Term Mitigations:

• Implement a hardware security module (HSM) for secure key storage.
• Use mutual TLS (mTLS) with client certificates.
• Regularly audit OTA update infrastructure for misconfigurations.

Detection & Monitoring:

• Deploy the YARA, Sigma, and Suricata rules provided above.
• Monitor for any unexpected TLS connections to Redbend domains.
• Alert on any firmware update failures or certificate validation errors.

Valters IT