Old Vulnerabilities, New Concerns: Spectre Fix Impacts Performance
Approximately six years ago, vulnerabilities were discovered that affected the majority of Intel and AMD processors. Known as Spectre and Meltdown, these flaws could be exploited to steal sensitive data from compromised systems.
In March 2022, Intel released an update addressing one variant of Spectre. In response, Microsoft implemented corresponding security measures in both client and server versions of Windows. However, these measures are disabled by default, likely due to their negative impact on performance.
On its Microsoft Security Response Center portal, Microsoft states:
“The vulnerability assigned to this CVE is in certain processor models offered by Intel and was initially disclosed March 8, 2022. Intel published updates April 9, 2024 and this CVE is being documented in the Security Update Guide to inform customers of the available mitigation and its potential performance impact. The mitigation for this vulnerability is disabled by default and manual action is required for customers to be protected.”
Thus, the Spectre vulnerability exploits features of processors that use branch prediction mechanisms or speculative execution. It also helps circumvent hardware security measures such as Enhanced Indirect Branch Restricted Speculation (EIBRS) or similar tools for ARM processors known as CSV2. This involves the use of the Branch History Buffer (BHB), which is why this second version of Spectre is also referred to as Spectre-BHB, Branch History Injection (BHI), or Branch Target Injection (BTI).
What steps are required to protect my system against the vulnerability?
We are providing the following registry information to enable the mitigations for this CVE.
Important: This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry see How to back up and restore the registry in Windows.
To enable the mitigation for CVE-2022-0001 on Windows devices and clients using Intel Processors:
- reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management” /v FeatureSettingsOverride /t REG_DWORD /d 0x00800000 /f
- reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management” /v FeatureSettingsOverrideMask /t REG_DWORD /d 0x00000003 /f
Customers who wish to implement the mitigation within their systems can also refer to the following for more information.
- Windows Server and Azure Stack HCI customers: See Microsoft Knowledge Base Article 4072698
- Windows client guidance for IT Pros: See Microsoft Knowledge Base Article 4073119
- Windows Device customers: See Microsoft Knowledge Base Article 4073757
To enable the mitigation for CVE-2022-0001 on Linux devices and clients using Intel Processors:
- Specify
spectre_bhi=onon the kernel command line. For more information about kernel command-line parameters see https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
