CVE-2021-28708 : Security Advisory and Response
Discover insights into CVE-2021-28708, a Xen vulnerability allowing DoS attacks. Learn about impacts, affected systems, and mitigation strategies for enhanced system security.
This CVE-2021-28708 article provides insights into a vulnerability in Xen that can be exploited by malicious or buggy guest kernels, potentially leading to a Denial of Service attack and other security risks. Learn about the impact, technical details, and mitigation strategies related to CVE-2021-28708.
Understanding CVE-2021-28708
CVE-2021-28708 involves PoD operations on misaligned GFNs in Xen, affecting x86 HVM and PVH guests. The vulnerability allows guests to control certain memory aspects, leading to potential system-wide issues.
What is CVE-2021-28708?
The vulnerability arises from the inadequate alignment enforcement of base page frame numbers during PoD operations, specifically in the XENMEM_decrease_reservation and XENMEM_populate_physmap operations.
The Impact of CVE-2021-28708
Malicious or buggy guest kernels exploiting this vulnerability can launch DoS attacks on the system. Additionally, there is a risk of privilege escalation and information leaks.
Technical Details of CVE-2021-28708
Find detailed technical information related to the vulnerability:
Vulnerability Description
The vulnerability allows guests to manipulate memory aspects, potentially leading to a host crash under specific conditions.
Affected Systems and Versions
Xen versions from 4.7 onwards are impacted, with versions older than 4.6 being unaffected. Specifically, x86 HVM and PVH guests running in PoD mode are vulnerable.
Exploitation Mechanism
The vulnerability can be exploited by initiating PoD operations that do not enforce proper alignment of base page frame numbers, leading to system-wide consequences.
Mitigation and Prevention
Discover effective strategies to mitigate the risks associated with CVE-2021-28708:
Immediate Steps to Take
Avoid starting x86 HVM or PVH guests in populate-on-demand mode to mitigate the vulnerability.
Long-Term Security Practices
Regularly update Xen to the patched versions to ensure the latest security enhancements are in place.
Patching and Updates
Apply patches provided by Xen promptly to address the vulnerability and enhance system security.