CVE-2020-15563 : Security Advisory and Response
Discover the Xen vulnerability in versions up to 4.13.x allowing x86 HVM guest OS users to crash the hypervisor, impacting the entire host. Learn about affected systems, exploitation, and mitigation steps.
An issue was discovered in Xen through 4.13.x, allowing x86 HVM guest OS users to cause a hypervisor crash due to an inverted conditional in x86 HVM guests' dirty video RAM tracking code.
Understanding CVE-2020-15563
This CVE identifies a vulnerability in Xen that can be exploited by x86 HVM guest OS users to crash the hypervisor, leading to a Denial of Service (DoS) affecting the entire host.
What is CVE-2020-15563?
The vulnerability in Xen through version 4.13.x allows x86 HVM guest OS users to crash the hypervisor by exploiting an inverted conditional in the dirty video RAM tracking code.
The Impact of CVE-2020-15563
- Affects Xen versions from 4.8 onwards, while versions 4.7 and earlier are not impacted
- Only x86 systems are affected; Arm systems are not vulnerable
- Only x86 HVM guests using shadow paging can exploit the vulnerability
- Requires active monitoring of a guest's video frame buffer for exploitation
- x86 PV guests and x86 HVM guests using hardware-assisted paging are not susceptible
Technical Details of CVE-2020-15563
This section provides detailed technical information about the vulnerability.
Vulnerability Description
The issue in Xen allows x86 HVM guest OS users to crash the hypervisor by manipulating the dirty video RAM tracking code through an inverted conditional.
Affected Systems and Versions
- Xen versions from 4.8 onwards are vulnerable
- Xen versions 4.7 and earlier are not affected
- Only x86 systems are impacted; Arm systems are not at risk
Exploitation Mechanism
- Only x86 HVM guests using shadow paging can exploit the vulnerability
- Active monitoring of a guest's video frame buffer is necessary for successful exploitation
- x86 PV guests and x86 HVM guests using hardware-assisted paging are not vulnerable
Mitigation and Prevention
Protecting systems from CVE-2020-15563 requires immediate actions and long-term security practices.
Immediate Steps to Take
- Apply patches provided by Xen to mitigate the vulnerability
- Monitor and restrict access to guest video frame buffers
Long-Term Security Practices
- Regularly update Xen to the latest secure versions
- Implement strict access controls and monitoring mechanisms
Patching and Updates
- Ensure timely installation of security patches released by Xen