CVE-2019-19579 : Exploit Details and Defense Strategies

A flaw in Xen versions up to 4.12.x allows attackers to gain privileged access to the host operating system through direct memory access (DMA) when an untrusted domain has access to a physical device without using assignable-add. This vulnerability stems from an inadequate fix for CVE-2019-18424.

Understanding CVE-2019-19579

This CVE highlights a security issue in Xen that can lead to privilege escalation through DMA attacks.

What is CVE-2019-19579?

Attackers can exploit this vulnerability to gain host OS privileges by conducting DMA attacks on host memory when an untrusted domain has access to a physical device.
The vulnerability arises due to an incomplete fix for a previous CVE, allowing untrusted guests to access devices without proper configuration.

The Impact of CVE-2019-19579

Systems allowing guests direct access to DMA-capable devices via PCI pass-through are vulnerable to privilege escalation attacks.
Systems not using PCI pass-through are not affected by this vulnerability.

Technical Details of CVE-2019-19579

This section delves into the technical aspects of the vulnerability.

Vulnerability Description

The flaw allows untrusted domains with access to physical devices to perform DMA attacks on the host memory, leading to privilege escalation.

Affected Systems and Versions

Xen versions up to 4.12.x are impacted by this vulnerability.

Exploitation Mechanism

Attackers exploit the incomplete fix for CVE-2019-18424, allowing untrusted domains to access physical devices without proper configuration, leading to DMA attacks.

Mitigation and Prevention

Protecting systems from CVE-2019-19579 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply patches and updates provided by Xen to address the vulnerability.
Restrict guest access to physical devices capable of DMA.

Long-Term Security Practices

Regularly update Xen and related software to mitigate potential vulnerabilities.
Implement strict device assignment and configuration policies to prevent unauthorized access.

Patching and Updates

Stay informed about security advisories and updates from Xen to apply patches promptly.