Privilege Escalation Vulnerability in Xen Package: CVE-2019-19579
Summary
ALPINE-CVE-2019-19579: An issue was discovered in Xen through 4.12.x allowing attackers to gain host OS privileges via DMA in a situation where an untrusted domain has access to a physical device (and assignable-add is not used), because of an... Affects xen versions < 4.12.2-r0. Fixed in 4.12.2-r0. How to fix ↓
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Background
Xen is an open-source hypervisor that allows multiple operating systems to run concurrently on a single physical machine. It is widely used for virtualization and cloud computing. The Xen package provides essential functionalities for managing virtual machines and their resources. However, it has been found vulnerable to a privilege escalation issue that can be exploited if certain configurations are not adhered to, particularly concerning device assignment and access control.
Vulnerability Detail
An issue was discovered in Xen through version 4.12.x that allows attackers to gain host OS privileges via Direct Memory Access (DMA) when an untrusted domain has access to a physical device. This vulnerability arises from an incomplete fix for CVE-2019-18424. The exploit can lead to privilege escalation, as an untrusted domain with access to a physical device can DMA into host memory, compromising the host system's integrity. The vulnerability primarily affects systems that utilize PCI passthrough, where guests are given direct access to physical devices capable of DMA.
How To Fix
Minimum fixed version
4.12.2-r0
This is the first release that contains the fix.
sudo apk add --upgrade xenTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, avoid using PCI passthrough for untrusted domains. Ensure that the 'assignable-add' feature of libxl is utilized to prepare devices for assignment to trusted guests only. This can prevent untrusted domains from accessing physical devices directly.
Conclusion
The CVE-2019-19579 vulnerability in the Xen package poses a significant risk of privilege escalation if not addressed. Users are encouraged to update their systems to the latest patched versions and implement recommended workarounds to mitigate potential risks. Regular monitoring for vulnerabilities using tools like Vulert can enhance security posture.
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FAQ
CVE-2019-19579 is a vulnerability in the Xen hypervisor that allows privilege escalation due to improper handling of Direct Memory Access (DMA) when untrusted domains access physical devices.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If exploited, this vulnerability can allow an attacker to gain host OS privileges, potentially leading to unauthorized access and control over the host system.
Yes, patches are available for various versions of the Xen package. Ensure to update to the latest patched version as specified in the 'how_to_fix' section.
The CVSS score for CVE-2019-19579 is 6.8, indicating a medium severity level.
References
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