CVE-2020-27213 : Security Advisory and Response

Ethernut Nut/OS 5.1 has a vulnerability that allows attackers to determine Initial Sequence Numbers (ISNs) for TCP connections, potentially leading to hijacking or spoofing.

Understanding CVE-2020-27213

What is CVE-2020-27213?

This CVE refers to a flaw in Ethernut Nut/OS 5.1 where the ISN generation for TCP connections is not sufficiently random, enabling attackers to predict ISNs.

The Impact of CVE-2020-27213

The vulnerability could allow attackers to hijack existing TCP connections or spoof future ones, compromising network security and integrity.

Technical Details of CVE-2020-27213

Vulnerability Description

The ISN generator in Ethernut Nut/OS 5.1 does not use a random enough source, making it possible for attackers to determine ISNs and exploit TCP connections.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions: All versions are affected

Exploitation Mechanism

Attackers can exploit the weak ISN generation to predict ISNs, enabling them to hijack ongoing TCP connections or create fake ones.

Mitigation and Prevention

Immediate Steps to Take

Implement network segmentation to limit the impact of potential attacks
Monitor network traffic for any unusual patterns or activities
Apply firewall rules to restrict unauthorized access

Long-Term Security Practices

Regularly update and patch the Ethernut Nut/OS software
Conduct security audits and assessments to identify and address vulnerabilities
Educate network administrators and users on best security practices

Patching and Updates

Apply patches and updates provided by Ethernut to address the ISN generation vulnerability.