CVE-2021-33541 Explained : Impact and Mitigation

Phoenix Contact Classic Line Controllers ILC1x0 and ILC1x1 in all versions/variants are affected by a Denial-of-Service vulnerability due to lack of authentication measures. Remote attackers can exploit this vulnerability using specially crafted IP packets to disrupt network communication. This article provides insights into the impact, technical details, and mitigation strategies for CVE-2021-33541.

Understanding CVE-2021-33541

This section delves into the details of the CVE-2021-33541 vulnerability affecting Phoenix Contact ILC1x Industrial controllers.

What is CVE-2021-33541?

Phoenix Contact's ILC1x0 and ILC1x1 controllers are susceptible to a Denial-of-Service vulnerability, allowing remote attackers to halt network communication by sending malicious IP packets that trigger the PLC's network communication module.

The Impact of CVE-2021-33541

The exploitation of this vulnerability can lead to a complete stoppage of network communication, requiring a device restart to restore connectivity. However, the automation tasks remain unaffected by this attack.

Technical Details of CVE-2021-33541

This section outlines the technical aspects of CVE-2021-33541, including the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability pertains to the absence of authentication measures in Phoenix Contact Classic Line Controllers ILC1x0 and ILC1x1, enabling remote attackers to disrupt network communication.

Affected Systems and Versions

ILC1x0 and ILC1x1 all variants are affected by this vulnerability within the Phoenix Contact Classic Line Controllers.

Exploitation Mechanism

Remote attackers exploit this vulnerability by sending specially crafted IP packets, initiating a Denial-of-Service condition on the PLC's network communication module.

Mitigation and Prevention

This section provides insights into mitigating the risks associated with CVE-2021-33541 through immediate and long-term security practices.

Immediate Steps to Take

Phoenix Contact recommends operating network-capable devices in closed networks or behind firewalls to mitigate the risk posed by this vulnerability.

Long-Term Security Practices

For long-term security, it is advised to follow the Phoenix Contact application note on measures to protect network-capable devices with Ethernet connections.

Patching and Updates

Stay informed about security updates and patches from Phoenix Contact to address vulnerabilities and secure your industrial controllers effectively.