CVE-2020-29485 : What You Need to Know
Discover the impact of CVE-2020-29485, a Xen vulnerability in versions 4.6 through 4.14.x allowing unbounded memory usage in oxenstored, potentially leading to a system-wide DoS attack. Learn how to mitigate and prevent this issue.
An issue was discovered in Xen 4.6 through 4.14.x that can lead to a system-wide DoS due to unbounded memory usage in oxenstored.
Understanding CVE-2020-29485
This CVE identifies a vulnerability in Xen versions 4.6 through 4.14.x that can be exploited by a guest to cause unbounded memory usage in oxenstored, potentially resulting in a system-wide Denial of Service (DoS) attack.
What is CVE-2020-29485?
Xen, in versions 4.6 through 4.14.x, is susceptible to a flaw where not all tracking information is freed when processing a guest XS_RESET_WATCHES request. This oversight allows a malicious guest to trigger unbounded memory consumption in oxenstored, leading to a potential system-wide DoS. It's important to note that only systems utilizing the Ocaml Xenstored implementation are at risk, while those using the C Xenstored implementation are not affected.
The Impact of CVE-2020-29485
The vulnerability poses a significant risk as it can be leveraged by an attacker to exhaust system memory resources, potentially resulting in a complete system outage or unresponsiveness.
Technical Details of CVE-2020-29485
Xen 4.6 through 4.14.x is affected by this vulnerability.
Vulnerability Description
When processing a guest XS_RESET_WATCHES request, Xen fails to release all tracking information, allowing a guest to exploit this flaw.
Affected Systems and Versions
- Xen versions 4.6 through 4.14.x
- Systems using the Ocaml Xenstored implementation
Exploitation Mechanism
An attacker with access to a guest VM can send a crafted XS_RESET_WATCHES request to trigger unbounded memory usage in oxenstored, potentially leading to a DoS condition.
Mitigation and Prevention
It is crucial to take immediate steps to address and mitigate the impact of CVE-2020-29485.
Immediate Steps to Take
- Apply patches provided by Xen to address the vulnerability.
- Monitor system resources for any unusual memory consumption.
Long-Term Security Practices
- Regularly update and patch Xen installations to protect against known vulnerabilities.
- Implement network segmentation and access controls to limit the attack surface.
Patching and Updates
- Xen has released patches to address this vulnerability. Ensure timely application of these patches to secure your systems.