CVE-2021-3418 : Security Advisory and Response

This article provides detailed information about CVE-2021-3418, a vulnerability in grub2 that can lead to the booting of unsigned kernels.

Understanding CVE-2021-3418

CVE-2021-3418 is a flaw in grub2 that allows the booting of unsigned kernels, impacting versions prior to 2.06 and systems using the shim_lock mechanism.

What is CVE-2021-3418?

The vulnerability allows grub to boot any kernel without signature validation, potentially leading to the booting of a tampered kernel in secureboot mode.

The Impact of CVE-2021-3418

This reintroduction of CVE-2020-15705 affects systems running grub2 versions earlier than 2.06. It poses a risk of loading malicious or compromised kernels.

Technical Details of CVE-2021-3418

This section delves into the vulnerability's description, affected systems and versions, as well as its exploitation mechanism.

Vulnerability Description

Certificates signed grub installed into the database can be booted directly, bypassing signature validation and potentially loading tampered kernels.

Affected Systems and Versions

CVE-2021-3418 affects versions of grub2 prior to 2.06 and systems utilizing the shim_lock mechanism.

Exploitation Mechanism

By exploiting this vulnerability, an attacker could boot a malicious kernel without signature checks, posing a serious security risk.

Mitigation and Prevention

Explore the immediate steps and long-term security practices to mitigate the risks posed by CVE-2021-3418.

Immediate Steps to Take

Users are advised to update their grub2 versions to 2.06 or higher and monitor for any unauthorized kernel boots.

Long-Term Security Practices

Implement secure boot configurations, regularly update system software, and conduct security assessments to avoid similar vulnerabilities.

Patching and Updates

Stay informed about security patches from grub2 providers and apply updates promptly to ensure a secure system.