CVE-2020-29486 Explained : Impact and Mitigation

An issue was discovered in Xen through 4.14.x where nodes in xenstore have ownership, allowing a malicious guest administrator to cause a denial of service against a specific guest or the whole host.

Understanding CVE-2020-29486

This CVE highlights a vulnerability in Xen that can be exploited by a guest to exhaust memory resources and disrupt the operation of other guests or the host system.

What is CVE-2020-29486?

The vulnerability in Xen through version 4.14.x allows a guest to manipulate node ownership in xenstore, potentially leading to a denial of service attack against specific guests or the entire host system.

The Impact of CVE-2020-29486

The exploitation of this vulnerability can result in a malicious guest administrator running xenstored out of memory, causing a denial of service against targeted guests or the entire host. All systems using oxenstored are vulnerable to this issue.

Technical Details of CVE-2020-29486

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The issue arises from the ownership of nodes in xenstore, where a guest can manipulate ownership, leading to quota implications and potential denial of service attacks.

Affected Systems and Versions

Systems using oxenstored through Xen version 4.14.x are vulnerable.
Systems using C xenstored are not affected.

Exploitation Mechanism

A malicious guest administrator can exploit the vulnerability by manipulating node ownership in xenstore, causing memory exhaustion and denial of service.

Mitigation and Prevention

To address CVE-2020-29486, follow these mitigation strategies:

Immediate Steps to Take

Apply patches provided by Xen to fix the vulnerability.
Monitor system resources for unusual behavior that may indicate a denial of service attack.

Long-Term Security Practices

Regularly update Xen and related components to ensure the latest security fixes are in place.
Implement strong access controls and isolation mechanisms to limit the impact of potential attacks.

Patching and Updates

Stay informed about security advisories from Xen and promptly apply patches to mitigate known vulnerabilities.