CVE-2021-34566 Explained : Impact and Mitigation

This article provides an overview of CVE-2021-34566, a vulnerability affecting WAGO I/O-Check Service in multiple products. It covers the impact, technical details, and mitigation strategies related to this vulnerability.

Understanding CVE-2021-34566

CVE-2021-34566 is a vulnerability found in WAGO I/O-Check Service, allowing an unauthenticated remote attacker to crash the iocheck process and write memory by sending a specially crafted packet containing OS commands.

What is CVE-2021-34566?

In WAGO I/O-Check Service in multiple products, an unauthenticated remote attacker can send a specially crafted packet containing OS commands to crash the iocheck process and write memory, resulting in loss of integrity and denial of service.

The Impact of CVE-2021-34566

The vulnerability, identified as CAPEC-100 Overflow Buffers, has a CVSS v3.1 base score of 9.1 (Critical). It poses a high impact on availability and integrity, without requiring any special privileges from the attacker.

Technical Details of CVE-2021-34566

The vulnerability is categorized under CWE-120 (Classic Buffer Overflow), highlighting the risk of buffer copy without checking the size of the input.

Vulnerability Description

The issue arises due to insufficient input validation in handling OS commands, allowing malicious actors to crash the iocheck process and write memory, leading to integrity loss and denial of service.

Affected Systems and Versions

Products like 750-81xx, 750-82xx, 752-8303, 762-4xxx, 762-5xxx, and 762-6xxx with FW1 version equal to or less than FW18 Patch 2 are impacted by this vulnerability.

Exploitation Mechanism

By sending specially crafted packets with OS commands, remote threat actors can exploit this vulnerability, causing system crashes and memory corruption.

Mitigation and Prevention

To safeguard against CVE-2021-34566, immediate steps and long-term security practices can minimize the risk and impact of the vulnerability.

Immediate Steps to Take

Apply security patches and updates provided by WAGO to fix the vulnerability.
Implement network segmentation and access controls to limit remote access to vulnerable systems.

Long-Term Security Practices

Regularly update and patch all software and firmware to prevent known vulnerabilities.
Conduct security audits and penetration testing to identify and mitigate potential weaknesses.

Patching and Updates

Stay informed about security advisories from WAGO and apply relevant patches promptly to ensure system security.