CVE-2021-41545 : What You Need to Know

A vulnerability in Siemens' Desigo DXR2, Desigo PXC3, Desigo PXC4, and Desigo PXC5 controllers could lead to a 'factory reset' state when receiving a specific BACnet protocol packet.

Understanding CVE-2021-41545

This CVE identifies a critical vulnerability in Siemens' building automation controllers.

What is CVE-2021-41545?

The vulnerability affects multiple Siemens products, leading to a 'factory reset' state due to an exception triggered by a specific BACnet protocol packet.

The Impact of CVE-2021-41545

The vulnerability can result in a loss of control and significant disruptions to building automation systems, potentially causing downtime and operational issues.

Technical Details of CVE-2021-41545

Siemens' controllers are vulnerable to an uncaught exception when receiving a specific BACnet protocol packet.

Vulnerability Description

When the affected controllers encounter the specified packet, it leads to an 'out of work' state, potentially causing a 'factory reset' operation.

Affected Systems and Versions

Desigo DXR2: All versions < V01.21.142.5-22
Desigo PXC3: All versions < V01.21.142.4-18
Desigo PXC4: All versions < V02.20.142.10-10884
Desigo PXC5: All versions < V02.20.142.10-10884

Exploitation Mechanism

The vulnerability is exploited through the reception of a specific BACnet protocol packet, triggering an unhandled exception that disrupts normal operation.

Mitigation and Prevention

Immediate Steps to Take:

Update affected systems to the patched versions provided by Siemens.
Implement network segmentation to minimize the exposure of controllers.
Monitor network traffic for any suspicious activity.

Long-Term Security Practices:

Regularly update firmware and software to address known vulnerabilities.
Train staff on cybersecurity best practices to prevent and respond to incidents effectively.
Conduct regular security assessments and penetration tests to identify and remediate potential risks.
Stay informed about security advisories and patches released by vendors.
Implement proper access controls and authentication mechanisms to restrict unauthorized access.

Patching and Updates: Siemens has released patched versions to address the vulnerability. It is crucial to apply these updates promptly to ensure the security of the affected systems.