Windows 10: ADV180016 | Microsoft Guidance for Lazy FP State Restore

  1. Posts : 30,100
    64-bit Windows 10 Pro build 17692
       1 Week Ago #1

    ADV180016 | Microsoft Guidance for Lazy FP State Restore

    Executive summary

    On January 3, 2018, Microsoft released an advisory and security updates related to a newly-discovered class of hardware vulnerabilities (known as Spectre and Meltdown) involving speculative execution side channels that affect AMD, ARM, and Intel CPUs to varying degrees. On June 13, 2018, an additional vulnerability involving side channel speculative execution, known as Lazy FP State Restore, has been announced and assigned CVE-2018-3665.

    An attacker, via a local process, could cause information stored in FP (Floating Point), MMX, and SSE register state to be disclosed across security boundaries on Intel Core family CPUs through speculative execution. An attacker must be able to execute code locally on a system in order to exploit this vulnerability, similar to the other speculative execution vulnerabilities. The information that could be disclosed in the register state depends on the code executing on a system and whether any code stores sensitive information in FP register state.

    The security boundaries that may be affected by this vulnerability include virtual machine, kernel, and process.

    Recommended actions

    1. Register for security notifications mailer to be alerted of content changes to this advisory. See Microsoft Technical Security Notifications.
    2. Review INTEL-SA-00145
    3. Apply security updates when they become available in a future Update Tuesday.


    1. Is Lazy restore enabled by default and can it be disabled?
    Lazy restore is enabled by default in Windows and cannot be disabled.

    2. Are VMs in Azure affected?
    Customers running VMs in Azure are not at risk from this variant. No action is required.

    3. What is the CVSS value for this vulnerability?
    CVSS - 4.3 Medium CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

    Product Platform Article Download Impact Severity Supersedence
    Updates forthcoming CVE-2018-3665 To be determined Information Disclosure Important


    Microsoft has not identified any mitigating factors for this vulnerability.


    Microsoft has not identified any workarounds for this vulnerability.


    Microsoft would like to thank Julian Stecklina from Amazon Germany, Thomas Prescher from Cyberus Technology GmbH, Zdenek Sojka from SYSGO AG, and Colin Percival for reporting this issue and working with us on coordinated disclosure.

    See acknowledgements for more information.


    The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.


    Version Date Description
    1.0 06/13/2018 Information published.


    See also:
      My ComputersSystem Spec

  2.    1 Week Ago #1

    Supposedly this vulnerability (which is related to Meltdown) has been known about for years, and the Linux kernel was quietly patched two years ago.
    Last edited by Ground Sloth; 1 Week Ago at 05:58.
      My ComputerSystem Spec

  3. Posts : 20,875
    Win10 Pro, Win10 Pro N, Win10 Home, Win10 Pro Insider Fast Ring, Windows 8.1 Pro, Ubuntu
       1 Week Ago #2

    New Lazy FP State Restore Vulnerability Affects All Intel Core CPUs
    Thankfully, researchers stated that this vulnerability would be difficult to execute via a web browser, so its impact is less than previous speculative execution vulnerabilities such as Meltdown. You can read more about the technical aspects of this vulnerability in this Twitter thread by Colin Percival.

    Click for full thread

    Intel has told BleepingComputer that this vulnerability has been addressed by oeprating system and hypervisor software for many years:

    "This issue, known as Lazy FP state restore, is similar to Variant 3a. It has already been addressed for many years by operating system and hypervisor software used in many client and data center products. Our industry partners are working on software updates to address this issue for the remaining impacted environments and we expect these updates to be available in the coming weeks. We continue to believe in coordinated disclosure and we are thankful to Julian Stecklina from Amazon Germany, Thomas Prescher from Cyberus Technology GmbH, Zdenek Sojka from SYSGO AG, and Colin Percival for reporting this issue to us. We strongly encourage others in the industry to adhere to coordinated disclosure as well."

    The good news is that this vulnerability does not require new CPU microcodes from Intel, but can be fixed instead by operating system updates. Since Intel's advisory was posted, various Linux distributions and Microsoft have posted advisories related to this new vulnerability.
      My ComputersSystem Spec

  4. Posts : 351
    Windows 10 Home April 2018 Update 64-bit
       1 Week Ago #3

    Meanwhile at the Intel Security Lab:

      My ComputerSystem Spec


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