CVE-2025-1468

Executive Summary

CVE-2025-1468 is a high-severity information disclosure vulnerability in the CODESYS OPC UA Server. An unauthenticated remote attacker can exploit the non-default Basic128Rsa15 security policy to gain access to sensitive information, including authentication credentials. This vulnerability has a CVSS score of 7.5, indicating a significant risk to confidentiality. No public proof-of-concept (PoC) or exploit code is currently available, and the patch status remains unknown. The EPSS score is 0.0%, suggesting low exploitation activity at this time, but the potential impact on industrial control systems (ICS) environments is severe.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects the CODESYS OPC UA Server, a component of the CODESYS development environment widely used in industrial automation and PLC programming. Organizations using CODESYS should treat this as a critical supply chain risk due to the potential for credential theft and subsequent lateral movement within OT networks.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network (AV:N) – Exploitable remotely without physical access.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Full disclosure of sensitive data, including authentication information.
• Integrity Impact: None (I:N) – No data modification possible.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: High. The vulnerability allows unauthenticated remote attackers to steal credentials, which can be used to compromise the entire CODESYS environment and potentially the underlying PLC or SCADA system.

Deep Dive & Mechanics

The CODESYS OPC UA Server implements the OPC UA (Unified Architecture) protocol for industrial communication. The Basic128Rsa15 security policy is a non-default configuration that uses a specific set of cryptographic algorithms (AES128, RSA with 1024-bit keys, and SHA-1). The vulnerability arises from a flaw in how the server handles authentication when this policy is enabled.

Root Cause: The server fails to properly validate or encrypt authentication tokens when using the Basic128Rsa15 policy, allowing an unauthenticated attacker to intercept or extract sensitive information, including usernames and passwords, from network traffic or server responses.

Attack Vector: An attacker on the same network as the CODESYS OPC UA Server can send specially crafted OPC UA requests using the Basic128Rsa15 security policy. The server responds with authentication data that should be protected but is instead exposed due to the implementation flaw.

Impact: Successful exploitation leads to the disclosure of authentication credentials, which can be reused to gain unauthorized access to the CODESYS runtime environment, modify PLC programs, or pivot to other systems in the OT network.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison cannot be provided. However, the vulnerability likely resides in the OPC UA stack's handling of the Basic128Rsa15 security policy. A patched version would need to:

1. Properly enforce encryption for authentication tokens when Basic128Rsa15 is selected.
2. Validate security policy parameters to prevent downgrade attacks.
3. Implement secure session management to prevent token reuse.

Hypothetical vulnerable code snippet (pseudocode):

# Vulnerable: Authentication token sent without proper encryption
def handle_opcua_request(request):
    if request.security_policy == "Basic128Rsa15":
        # Token is exposed in plaintext or weakly encrypted
        return {"status": "success", "token": user_authentication_token}

Hypothetical patched code snippet (pseudocode):

# Patched: Token is encrypted with session key
def handle_opcua_request(request):
    if request.security_policy == "Basic128Rsa15":
        encrypted_token = encrypt_with_session_key(user_authentication_token)
        return {"status": "success", "token": encrypted_token}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Target: CODESYS OPC UA Server (version unknown) with Basic128Rsa15 security policy enabled.
• Attacker Machine: Kali Linux with Python 3 and OPC UA libraries (e.g., opcua-asyncio).
• Network: Both machines on the same subnet.

Exploitation Steps:

1. Scan for OPC UA servers: Use a tool like opcua-client to discover servers.
2. Identify security policies: Connect to the server and enumerate supported policies.
3. Craft malicious request: Send a request using Basic128Rsa15 policy to trigger the vulnerability.
4. Extract credentials: Parse the server response for authentication tokens.

Example Python script (conceptual):

from opcua import Client

client = Client("opc.tcp://target_ip:4840")
client.set_security_policy("Basic128Rsa15")
client.connect()
# The server may leak credentials in the response
response = client.get_authentication_info()
print("Extracted credentials:", response)
client.disconnect()

Note: No public exploit code is available. This is a conceptual demonstration.

Blue Team (Defensive)

Detection:

• Monitor for OPC UA connections using the Basic128Rsa15 security policy.
• Alert on unusual authentication patterns or repeated failed connections.
• Use network monitoring to detect anomalous OPC UA traffic.

Mitigation:

• Disable the Basic128Rsa15 security policy if not required.
• Use stronger security policies (e.g., Basic256Sha256).
• Implement network segmentation to isolate OPC UA servers.
• Apply vendor patches as soon as they become available.

Indicators of Compromise (IOCs)

• Network Traffic:
  • OPC UA connections using Basic128Rsa15 security policy (identified by specific security header bytes).
  • Unusual authentication token patterns in OPC UA responses.
• Logs:
  • CODESYS OPC UA Server logs showing connections with Basic128Rsa15 policy.
  • Repeated authentication failures followed by successful logins.
• Files:
  • No specific file-based IOCs known.

Example YARA rule for network traffic:

rule OPCUA_Basic128Rsa15_Exploit {
    meta:
        description = "Detects OPC UA traffic using Basic128Rsa15 security policy"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $policy = { 42 61 73 69 63 31 32 38 52 73 61 31 35 } // "Basic128Rsa15"
    condition:
        $policy
}

Detection Engineering

YARA Rule

rule CVE_2025_1468_OPCUA_Leak {
    meta:
        description = "Detects potential exploitation of CVE-2025-1468 in CODESYS OPC UA Server"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-1468"
    strings:
        $auth_token = /[A-Za-z0-9+/=]{20,40}/ // Base64-like token
        $policy_ref = "Basic128Rsa15"
    condition:
        $policy_ref and #auth_token > 2
}

Sigma Rule

title: CVE-2025-1468 CODESYS OPC UA Credential Leak
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects network traffic indicating exploitation of CVE-2025-1468
author: Valters IT
date: 2025-04-10
logsource:
    category: network_connection
    product: zeek
detection:
    selection:
        service: "opcua"
        security_policy: "Basic128Rsa15"
    condition: selection
falsepositives:
    - Legitimate use of Basic128Rsa15 policy
level: high

Suricata Rule

alert tcp any any -> any 4840 (msg:"CVE-2025-1468 CODESYS OPC UA Basic128Rsa15 Exploit"; flow:to_server,established; content:"|42 61 73 69 63 31 32 38 52 73 61 31 35|"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Basic128Rsa15 security policy on all CODESYS OPC UA Servers.
2. Use stronger security policies such as Basic256Sha256 or Basic256.
3. Restrict network access to OPC UA servers using firewalls and VLANs.
4. Monitor for unauthorized access attempts and credential leaks.

Long-Term Fixes:

• Apply vendor patches as soon as they are released.
• Conduct a security audit of all CODESYS installations.
• Implement OPC UA security best practices, including certificate-based authentication.
• Train staff on secure configuration of industrial control systems.

Workaround:

• If Basic128Rsa15 is required for legacy compatibility, implement additional network-level encryption (e.g., VPN) to protect traffic.

Report generated by Valters IT DevSecOps & CTI Division