CVE-2021-34581 Explained : Impact and Mitigation

A Denial of Service vulnerability has been discovered in the OpenSSL implementation of WAGO devices, specifically affecting versions FW4 up to FW15. This vulnerability allows an unauthenticated attacker to cause a Denial of Service (DoS) on the device.

Understanding CVE-2021-34581

In this section, we will dive into the details of CVE-2021-34581.

What is CVE-2021-34581?

The CVE-2021-34581 vulnerability involves a Missing Release of Resource after Effective Lifetime issue in the OpenSSL implementation of WAGO 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889 devices.

The Impact of CVE-2021-34581

The vulnerability can be exploited by an attacker to launch a DoS attack on the affected device, leading to service unavailability.

Technical Details of CVE-2021-34581

Let's explore the technical aspects of CVE-2021-34581.

Vulnerability Description

The vulnerability arises due to a flaw in how resources are released in the OpenSSL implementation, allowing an unauthenticated attacker to disrupt device services.

Affected Systems and Versions

WAGO devices including 750-831/xxx-xxx, 750-880/xxx-xxx, 750-881, 750-889 running FW4 up to FW15 are impacted by this vulnerability.

Exploitation Mechanism

The vulnerability can be exploited over the network without the need for any special privileges, making it a significant threat to device availability.

Mitigation and Prevention

To secure your systems against CVE-2021-34581, consider the following mitigation strategies:

Immediate Steps to Take

Update the device to the latest firmware version ( >FW15 ).
Restrict network access to the device.
Avoid direct internet connections.

Long-Term Security Practices

Disable unused TCP/UDP ports.
Disable Web-Based Management ports 80/443 after the configuration phase.

Patching and Updates

Regularly check for firmware updates and security patches from WAGO to protect your devices from potential vulnerabilities.