CVE-2020-25602 : Vulnerability Insights and Analysis

An issue was discovered in Xen through 4.14.x where an x86 PV guest can trigger a host OS crash when handling guest access to MSR_MISC_ENABLE.

Understanding CVE-2020-25602

This vulnerability affects Xen versions 4.11 and onwards.

What is CVE-2020-25602?

An x86 PV guest can crash the host OS by accessing certain Model Specific Registers without error handling.
Only x86 systems without the MISC_ENABLE MSR (0x1a0) are vulnerable.
AMD and Hygon systems are vulnerable, while Intel systems are not.

The Impact of CVE-2020-25602

A buggy or malicious PV guest administrator can crash Xen, leading to a host Denial of Service.
Only x86 PV guests can exploit the vulnerability; x86 HVM/PVH guests cannot.

Technical Details of CVE-2020-25602

This section provides detailed technical information about the vulnerability.

Vulnerability Description

Xen allows an x86 PV guest to crash the host OS by mishandling guest access to MSR_MISC_ENABLE.

Affected Systems and Versions

Only x86 systems running Xen versions 4.11 and onwards are vulnerable.

Exploitation Mechanism

The vulnerability is triggered when a PV guest accesses certain Model Specific Registers without error handling.

Mitigation and Prevention

Learn how to mitigate and prevent the exploitation of CVE-2020-25602.

Immediate Steps to Take

Update Xen to a non-vulnerable version.
Implement proper error handling for guest access to Model Specific Registers.

Long-Term Security Practices

Regularly update Xen and apply security patches.
Monitor and restrict guest access to critical system registers.
Conduct security audits to detect and address vulnerabilities.

Patching and Updates

Apply patches provided by Xen to address the vulnerability.