CVE-2019-6841 Explained : Impact and Mitigation

The Modicon M580, Modicon M340, and Modicon BMxCRA and 140CRA modules are vulnerable to a CWE-755 flaw that can lead to a Denial of Service attack on the PLC.

Understanding CVE-2019-6841

What is CVE-2019-6841?

The CVE-2019-6841 vulnerability involves an Improper Handling of Exceptional Conditions in Modicon M580, Modicon M340, and Modicon BMxCRA / 140CRA modules, potentially allowing a Denial of Service attack on the PLC.

The Impact of CVE-2019-6841

The vulnerability can be exploited by upgrading the firmware without a firmware image inside the package using the FTP protocol, affecting the availability and functionality of the affected systems.

Technical Details of CVE-2019-6841

Vulnerability Description

The flaw in Modicon M580, Modicon M340, and Modicon BMxCRA / 140CRA modules allows for a Denial of Service attack when upgrading firmware without a firmware image using FTP.

Affected Systems and Versions

All versions for Modicon M340 and Modicon BMxCRA / 140CRA modules are affected.
Versions prior to V3.10 for Modicon M580 are vulnerable.

Exploitation Mechanism

The vulnerability can be exploited by malicious actors through the firmware upgrade process using the FTP protocol.

Mitigation and Prevention

Immediate Steps to Take

Apply patches and updates provided by the vendor.
Implement network segmentation to limit exposure.
Monitor network traffic for any suspicious activities.

Long-Term Security Practices

Regularly update firmware and software to the latest versions.
Conduct security assessments and penetration testing.
Educate users on secure firmware upgrade procedures.

Patching and Updates

Schneider Electric may release patches to address the vulnerability.