CVE-2021-28693 : Security Advisory and Response

A vulnerability in Xen affects the boot modules on Arm systems, potentially exposing sensitive information to unauthorized domains post-boot.

Understanding CVE-2021-28693

This vulnerability in Xen impacts the Arm systems by failing to scrub boot modules, leading to a risk of sensitive data exposure.

What is CVE-2021-28693?

The issue arises from the bootloader not clearing sensitive boot modules data before handing it over to the allocator, leaving a window for unauthorized access.

The Impact of CVE-2021-28693

Sensitive information from the boot modules might be visible to another domain after boot, posing a security risk.

Technical Details of CVE-2021-28693

The vulnerability allows for potential data leakage due to unscrubbed boot modules on Arm-based systems.

Vulnerability Description

Xen fails to properly scrub boot modules on Arm systems, creating an opportunity for data exposure between domains.

Affected Systems and Versions

Arm systems running Xen versions since 4.12 are vulnerable to this issue, especially when boot scrubbing is disabled.

Exploitation Mechanism

By taking advantage of the unscrubbed boot modules, threat actors can access sensitive data from other domains post-boot.

Mitigation and Prevention

Understanding the immediate steps and long-term practices to mitigate and prevent the CVE-2021-28693 vulnerability.

Immediate Steps to Take

There is no available mitigation for this issue, emphasizing the need for thorough monitoring and security measures to prevent data leaks.

Long-Term Security Practices

Enabling boot scrubbing and ensuring regular security updates can minimize the risk of data exposure due to unscrubbed boot modules.

Patching and Updates

Staying updated with the latest Xen patches and ensuring boot scrubbing is enabled can help safeguard Arm systems against potential data breaches.