CVE-2020-15705 : What You Need to Know

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This impacts systems where the kernel signing certificate is directly imported into the secure boot database and GRUB image is booted without shim.

Understanding CVE-2020-15705

This CVE affects GRUB2 versions prior to 2.04 and has a CVSS base score of 6.4.

What is CVE-2020-15705?

CVE-2020-15705 is a vulnerability in GRUB2 that allows bypassing secure boot by not validating the kernel signature when booted directly without shim.

The Impact of CVE-2020-15705

CVSS Base Score: 6.4 (Medium)
Attack Vector: Local
Attack Complexity: High
Privileges Required: High
Confidentiality Impact: High
Integrity Impact: High
Availability Impact: High

Technical Details of CVE-2020-15705

This section provides more in-depth technical details about the vulnerability.

Vulnerability Description

GRUB2 fails to validate the kernel signature when directly booted without shim, allowing the bypass of secure boot mechanisms.

Affected Systems and Versions

Affected Versions: GRUB2 versions prior to 2.04
Affected Systems: Systems where the kernel signing certificate is directly imported into the secure boot database and GRUB image is booted without shim.

Exploitation Mechanism

The vulnerability can be exploited by booting the GRUB image directly without using shim, bypassing the secure boot process.

Mitigation and Prevention

To address CVE-2020-15705, follow these mitigation strategies:

Immediate Steps to Take

Update GRUB2 to a version that includes the fix.
Implement secure boot best practices.

Long-Term Security Practices

Regularly update and patch GRUB2 and other critical software.
Monitor security advisories for related vulnerabilities.

Patching and Updates

Apply patches provided by the vendor to fix the vulnerability and ensure secure boot mechanisms are properly configured.