CVE-2020-15706 Explained : Impact and Mitigation

GRUB2 contains a race condition leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, potentially allowing arbitrary code execution and secure boot restriction bypass.

Understanding CVE-2020-15706

This CVE involves a vulnerability in GRUB2 that could be exploited to execute arbitrary code and bypass secure boot restrictions.

What is CVE-2020-15706?

GRUB2 has a race condition in grub_script_function_create() that leads to a use-after-free vulnerability.
The issue affects GRUB2 version 2.04 and earlier versions.

The Impact of CVE-2020-15706

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-2020-15706

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

Vulnerability Description

The vulnerability arises from a race condition in grub_script_function_create() in GRUB2.
It can result in a use-after-free scenario, potentially leading to arbitrary code execution.

Affected Systems and Versions

Affected Versions:
Ubuntu 20.04 LTS (less than 2.04-1ubuntu26.1)
Ubuntu 18.04 LTS (less than 2.02-2ubuntu8.16)
Ubuntu 16.04 LTS (less than 2.02~beta2-36ubuntu3.26)
Ubuntu 14.04 ESM (less than 2.02~beta2-9ubuntu1.20)

Exploitation Mechanism

The vulnerability can be exploited by redefining a function while the same function is already executing, triggering the use-after-free condition.

Mitigation and Prevention

Protecting systems from this vulnerability is crucial to maintaining security.

Immediate Steps to Take

Apply security patches provided by the vendor.
Monitor vendor advisories for updates and follow best security practices.

Long-Term Security Practices

Regularly update and patch all software components.
Implement secure boot configurations and follow secure coding practices.

Patching and Updates

Refer to vendor-specific security advisories for patching instructions and updates.