CVE-2019-20790 : What You Need to Know

OpenDMARC versions 1.3.2 and 1.4.x, when used with pypolicyd-spf 2.0.2, are susceptible to attacks that can bypass SPF and DMARC authentication when the HELO field does not match the MAIL FROM field.

Understanding CVE-2019-20790

In situations where the HELO field does not match the MAIL FROM field, OpenDMARC versions 1.3.2 and 1.4.x, when combined with pypolicyd-spf 2.0.2, can be vulnerable to attacks that circumvent SPF and DMARC authentication.

What is CVE-2019-20790?

CVE-2019-20790 is a vulnerability in OpenDMARC versions 1.3.2 and 1.4.x, in conjunction with pypolicyd-spf 2.0.2, that allows attackers to bypass SPF and DMARC authentication when there is inconsistency between the HELO and MAIL FROM fields.

The Impact of CVE-2019-20790

This vulnerability can be exploited by malicious actors to circumvent SPF and DMARC authentication, potentially leading to unauthorized access and email spoofing.

Technical Details of CVE-2019-20790

OpenDMARC versions 1.3.2 and 1.4.x, when used with pypolicyd-spf 2.0.2, are affected by the following technical details:

Vulnerability Description

The vulnerability allows attackers to bypass SPF and DMARC authentication when the HELO field does not match the MAIL FROM field.

Affected Systems and Versions

OpenDMARC versions 1.3.2 and 1.4.x
pypolicyd-spf 2.0.2

Exploitation Mechanism

Attackers exploit the inconsistency between the HELO and MAIL FROM fields to bypass SPF and DMARC authentication.

Mitigation and Prevention

To address CVE-2019-20790, consider the following mitigation strategies:

Immediate Steps to Take

Update OpenDMARC to a patched version that addresses the vulnerability.
Monitor email authentication logs for suspicious activities.

Long-Term Security Practices

Implement strict email authentication policies to prevent spoofing.
Conduct regular security assessments to identify and mitigate email-related vulnerabilities.

Patching and Updates

Apply patches provided by OpenDMARC and pypolicyd-spf to fix the vulnerability.