AMD: CVE-2023-20569 Return Address Predictor

Why is this AMD CVE included in the Security Update Guide? The vulnerability assigned to this CVE is in certain processor models offered by AMD. The mitigation for this vulnerability requires a Windows update. This CVE is being documented in the Security Update Guide to announce that the latest builds of Windows enable the mitigation and provide protection against the vulnerability. Please see the following for more information: AMD-SB-7005

Are any additional steps required to protect my system after installing the August Windows updates? Customers who allow untrusted users to execute arbitrary code might wish to implement some extra security features within their systems. These features protect against the intra-process disclosure vectors that this speculative execution vulnerability describes. See the following for more information. Microsoft Windows client customers: See Microsoft Knowledge Base Article 4073119. Microsoft Windows Server/Azure Stack HCI customers: See Microsoft Knowledge Base Article 4072698 for additional information, including workarounds. Microsoft Azure has taken steps to address the security vulnerabilities at the hypervisor level to protect VMs running in Azure. More information can be found here. Can I expect any performance impact after I configure the registry keys? In some cases, installing these updates will have a performance impact. In testing Microsoft has seen some performance impact with these mitigations, in particular when hyperthreading is disabled. Microsoft values the security of its software and services and has made the decision to implement certain mitigation strategies in an effort to better secure our products. In some cases, mitigations are not enabled by default to allow users and administrators to evaluate the performance impact and risk exposure before deciding to enable the mitigations. We continue to work with hardware vendors to improve performance while maintaining a high level of security. Are Microsoft Azure assets protected? Microsoft is in the process of deploying mitigations across our cloud services and we expect this work to be complete soon. More information is available here. How do I know if I am affected? Please refer to AMD advisory AMD-SB-7005 to determine which AMD CPUs are affected.

How does this vulnerability affect Azure? This vulnerability affected a limited set of Azure Virtual Machine offerings using certain AMD EPYC processors. An update is being deployed across Azure infrastructure and the majority of customers are secured in the process automatically. Most customers do not need to take any action.

Is there any action Azure customers need to take? The majority of Azure customers are mitigated automatically by the update deployed across Azure and do not need to take any action. However, a small subset of customers with custom Maintenance Configurations on their Azure Virtual Machines may need to take action to apply the update. These customers will receive additional messaging through the Azure Portal via Azure Service Health with additional guidance.