Siemens TeleControl Server Basic SQL Injection Vulnerabilities: Critical Risks and Mitigations

Siemens TeleControl Server Basic (TCSB) has been identified with multiple critical SQL injection vulnerabilities affecting versions prior to V3.1.2.2. These vulnerabilities, tracked under 66 distinct CVEs including CVE-2025-27495 and CVE-2025-29931, could allow attackers to execute arbitrary code with NT AUTHORITY\NetworkService permissions, manipulate databases, and cause denial-of-service conditions. The affected software is widely deployed in critical infrastructure sectors including energy, water systems, and transportation worldwide.

Executive Summary

The vulnerabilities in Siemens TCSB represent a significant risk to industrial control systems, with the most severe cases scoring 9.8 in CVSS v3.1. Attackers exploiting these flaws could gain complete control over affected systems through port 8000, which serves as the primary attack vector. Siemens has released version V3.1.2.2 to address these issues, along with interim mitigation strategies for organizations unable to immediately patch.

Key points about the vulnerabilities:

CVSS Scores: Ranging from 8.7 to 9.8 (Critical)
Attack Vector: Network exploitable with low complexity
Authentication: Some vulnerabilities require authentication while others don’t
Impact: Code execution, data manipulation, and system compromise

Technical Details of the Vulnerabilities

The SQL injection vulnerabilities affect multiple internal methods of the TCSB application, including CreateTrace, VerifyUser, and Authenticate. Successful exploitation allows attackers to bypass authorization controls and execute SQL commands through crafted inputs. The most severe vulnerabilities (CVE-2025-27495, CVE-2025-27539, CVE-2025-27540) require no authentication and can be exploited remotely.

According to Siemens’ security advisory SSA-443402¹, the affected methods span core functionality including project management, user administration, and system configuration. The vulnerabilities were discovered through coordinated disclosure by Trend Micro’s Zero Day Initiative and Siemens’ internal security teams.

System Architecture and Affected Components

TCSB serves as middleware for industrial control systems, managing communication between stations through various protocols including OPC DA/UA. The system organizes infrastructure into logical projects, with configuration limits that vary by license tier (64-5000 stations). The SQL Server 2014 Express database backend handles all configuration and operational data, making it the primary target of these vulnerabilities.

Redundant configurations, while improving availability, introduce additional attack surfaces through synchronization mechanisms on port 8000. The system’s architecture allows for both permanent TCP connections and temporary on-demand links, with multicast commands for remote management. These features, while operationally useful, expand the potential impact of the identified vulnerabilities.

Mitigation Strategies and Best Practices

Siemens recommends immediate patching to version V3.1.2.2 as the primary mitigation. For organizations requiring additional time for testing and deployment, network-level controls can reduce risk:

“Restrict access to port 8000 on the affected systems to trusted IP addresses only. Disable redundancy features if not required for operations.”

Additional security measures should include:

Implementation of VPNs for remote access
Regular review of SQL Server Agent jobs and permissions
Monitoring of Dynamic Management Views for unusual database activity
Application of defense-in-depth strategies recommended by CISA²

Operational Impact and Detection

Organizations using TCSB should monitor for unusual database activity, particularly unexpected changes to system configurations or user permissions. The SQL Server’s built-in monitoring capabilities, including Dynamic Management Views like sys.dm_sql_referencing_entities, can help identify suspicious queries:

USE TCSB_Database;
SELECT referencing_schema_name, referencing_entity_name 
FROM sys.dm_sql_referencing_entities('dbo.Users', 'OBJECT');

This query can help identify unauthorized access attempts to sensitive tables. Network monitoring should focus on port 8000 traffic, with particular attention to unusual connection patterns or bulk data transfers.

Conclusion

The Siemens TCSB vulnerabilities represent a critical threat to industrial control systems, with potential impacts ranging from operational disruption to complete system compromise. While patches are available, the complexity of industrial environments often requires extended deployment timelines. Organizations should prioritize risk reduction through network segmentation, access controls, and enhanced monitoring while working toward complete remediation.

The coordinated disclosure process involving Trend Micro and Siemens demonstrates the value of industry collaboration in addressing complex security challenges. Continued vigilance and prompt patching remain essential for maintaining the security of critical infrastructure systems.