CVE-2020-5956 Explained : Impact and Mitigation

An issue was discovered in SdLegacySmm in Insyde InsydeH2O with kernel 5.1 before 05.15.11, 5.2 before 05.25.11, 5.3 before 05.34.11, and 5.4 before 05.42.11. The software SMI handler allows untrusted external input because it does not verify CommBuffer.

Understanding CVE-2020-5956

This CVE involves a vulnerability in the SdLegacySmm component of Insyde InsydeH2O firmware.

What is CVE-2020-5956?

The issue in SdLegacySmm allows untrusted external input due to a lack of verification in the CommBuffer, potentially leading to security breaches.

The Impact of CVE-2020-5956

This vulnerability could be exploited by attackers to inject malicious code or commands, compromising the system's integrity and confidentiality.

Technical Details of CVE-2020-5956

This section provides more in-depth technical insights into the CVE.

Vulnerability Description

The vulnerability arises from the SMI handler's failure to validate external input, specifically the CommBuffer, creating a security risk.

Affected Systems and Versions

Insyde InsydeH2O firmware with kernel versions 5.1 to 5.4 before specific build numbers are vulnerable.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending unverified input to the SMI handler, potentially executing unauthorized actions on the system.

Mitigation and Prevention

Protecting systems from CVE-2020-5956 requires immediate actions and long-term security measures.

Immediate Steps to Take

Update the firmware to the latest version that includes patches for this vulnerability.
Monitor system logs for any suspicious activities that might indicate exploitation attempts.

Long-Term Security Practices

Implement strict input validation mechanisms in firmware to prevent similar vulnerabilities.
Conduct regular security audits and penetration testing to identify and address potential weaknesses.

Patching and Updates

Regularly check for firmware updates from Insyde and apply patches promptly to mitigate known vulnerabilities.