CVE-2025-11043: Automation Studio Certificate Flaw

CVE-2025-11043 Overview

CVE-2025-11043 is an Improper Certificate Validation vulnerability affecting the OPC-UA client and ANSL over TLS client components in B&R Automation Studio. This flaw exists in versions before 6.5 and could allow an unauthenticated attacker positioned on the network to intercept and interfere with data exchanges, potentially enabling man-in-the-middle (MITM) attacks against industrial automation systems.

Critical Impact
Unauthenticated network attackers can intercept and manipulate industrial control communications, potentially compromising operational integrity in critical infrastructure environments.

Affected Products

B&R Automation Studio versions before 6.5
OPC-UA client components in affected Automation Studio versions
ANSL over TLS client components in affected Automation Studio versions

Discovery Timeline

2026-01-19 - CVE CVE-2025-11043 published to NVD
2026-01-19 - Last updated in NVD database

Technical Details for CVE-2025-11043

Vulnerability Analysis

This vulnerability stems from improper certificate validation (CWE-295) in the OPC-UA client and ANSL over TLS client implementations within B&R Automation Studio. When establishing secure TLS connections, the affected clients fail to properly validate server certificates, creating an opportunity for attackers to intercept encrypted communications.

The vulnerability is network-exploitable without requiring authentication or user interaction, though some preconditions must be met for successful exploitation. An attacker who can position themselves on the network path between the Automation Studio client and the target server can present a fraudulent certificate that would be accepted by the vulnerable client, enabling decryption and modification of traffic that should be protected by TLS.

The impact is significant for confidentiality and integrity, as attackers can both read sensitive data being transmitted and potentially inject malicious commands into the communication stream. This is particularly concerning in industrial automation contexts where OPC-UA is widely used for supervisory control and data acquisition (SCADA) communications.

Root Cause

The root cause is a failure to properly implement certificate chain validation, hostname verification, or certificate revocation checking in the TLS handshake process. This allows the client to accept certificates that should be rejected, including self-signed certificates, expired certificates, or certificates issued for different hostnames.

Attack Vector

An attacker must first position themselves on the network between the Automation Studio client and the target OPC-UA or ANSL server—typically achieved through ARP spoofing, DNS poisoning, or compromising network infrastructure. Once in position, the attacker can intercept the TLS handshake and present their own certificate. Due to the improper validation, the client accepts this fraudulent certificate, establishing a connection with the attacker instead of the legitimate server. The attacker can then proxy requests to the real server while reading or modifying all traffic in transit.

The vulnerability manifests during the TLS handshake phase when the client evaluates the server's certificate. Rather than generating synthetic code examples, refer to the BR Automation Security Advisory for specific technical details regarding the certificate validation flaw.

Detection Methods for CVE-2025-11043

Indicators of Compromise

Unexpected certificate warnings or changes in TLS certificate fingerprints for OPC-UA server connections
Network traffic anomalies indicating ARP spoofing or DNS poisoning attempts
Suspicious modifications to automation commands or unexpected process behavior
TLS connections being established with untrusted or self-signed certificates

Detection Strategies

Monitor network traffic for certificate mismatches between expected and observed server certificates
Deploy network intrusion detection systems (NIDS) to identify MITM attack patterns
Implement certificate pinning monitoring to detect unauthorized certificate usage
Review Automation Studio connection logs for authentication or connection anomalies

Monitoring Recommendations

Enable verbose logging for OPC-UA and ANSL client connections to capture certificate details
Monitor for ARP cache poisoning attempts using network security tools
Implement network segmentation monitoring for industrial control system networks
Configure alerts for TLS handshake failures or certificate validation warnings

How to Mitigate CVE-2025-11043

Immediate Actions Required

Upgrade B&R Automation Studio to version 6.5 or later immediately
Review network architecture to ensure proper segmentation of industrial control systems
Implement network monitoring to detect potential MITM attacks
Audit current OPC-UA and ANSL connections for signs of compromise

Patch Information

B&R Automation has addressed this vulnerability in Automation Studio version 6.5. Organizations should upgrade to this version or later to remediate the improper certificate validation flaw. Detailed patch information is available in the BR Automation Security Advisory.

Workarounds

Implement strict network segmentation to isolate industrial control systems from untrusted networks
Use VPN tunnels or other encrypted channels for OPC-UA communications until patching is complete
Deploy network access controls to limit which systems can communicate with OPC-UA servers
Consider implementing certificate pinning at the network layer using security appliances

bash

# Network segmentation verification example
# Ensure industrial control networks are properly isolated

# Verify firewall rules restrict access to OPC-UA ports (typically 4840)
iptables -L -n | grep 4840

# Monitor for suspicious ARP activity
arp -a | grep -i automation