Dell EMC VxRail Software Update – Spectre Guest OS leakage mitigation

I posted earlier in the year that Dell EMC had released a Security Advisory to address Spectre (Meltdown doesn’t really affect VMware and hence VxRail).

One of the items that wasn’t addressed in the original fix was Guest OS leakage mitigation between processes within the VM – this required CPU/BIOS microcode updates which were not yet available from Intel.

Those updates were made available from Intel at the beginning of April and it’s taken a while for it to filter through to vSphere and VxRail – the delay is down to VxRail being a fully turn-key appliance which means all software/firmware updates from Dell EMC are fully tested and validated before release.

Updates 4.0.402 and 4.5.152 are now available to download from Dell EMC’s support portal.

Release notes can be found here:

The accompanying Dell EMC Security Advisory is available here: DSA-2018-074: Dell EMC VxRail Security Update for Multiprocessor Side-Channel Analysis Attacks (Meltdown and Spectre)

VxRail Appliance software 4.0.402 and 4.5.152 contains the Intel microcode fix to complete the resolution of the speculative execution security issues.
VxRail Appliance software 4.0.402 includes fixes for the following security vulnerabilities:

  1. CVE-2017-5753 (Variant 1: bounds check bypass, also known as Spectre) – Complete fix in 4.0.401 and above.
  2. CVE-2017-5715 (Variant 2: branch target injection, also known as Spectre):
    • Mitigates leakage from the hypervisor or guest VMs into a malicious guest VM – Complete fix in 4.0.401 and above.
    • Guest OS leakage mitigation between processes within the VM requires BIOS or CPU microcode update released by Intel and included in this release – Complete fix with either BIOS or CPU microcode update automatically applied through the VxRail 4.0.402 automated software upgrade. No manual BIOS update required for any supported VxRail hardware platforms.
  3. CVE-2017-5754 (Variant 3: rogue data cache load, also known as Meltdown): Does not affect VxRail Appliance.

NOTE: Manual steps are required after the VxRail Appliance software upgrade to 4.0.402 to power cycle the VMs for branch target injection to take effect. More info available within this KB article:

Also note that this update does not patch Guest OS!

For more information about Spectre/Meltdown, have a meander to my original posts:
Spectre & Meltdown Vulnerabilities
Spectre & Meltdown Update


Spectre & Meltdown Update

So it seems that the microcode patches released by VMware associated with their recent Security Advisory (VMSA-2018-0004) have been pulled….
So that’s ESXi650-201801402-BG, ESXi600-201801402-BG, or ESXi550-201801401-BG.

The microcode patch provided by Intel was buggy and there seems to be issues when VMs access the new speculative execution control mechanism (Haswell & Broadwell processors). However, I can’t seem to find much around what these issues are…

For the time being, if you haven’t applied one of those microcode patches, VMware recommends not doing so and to apply the patches listed in VMSA-2018-0002 instead.

If you have applied the latest patches you will have to edit the config files of each ESXi host and add in a line that hides the new speculative execution control mechanism and reboot the VMs on that host. Detailed information can be found in the KB above.


Finally William Lam has created a very handy PowerCLI script that will help provide information about your existing vSphere environment and help identify whether you have hosts that are impacted by Spectre and this new Intel Sighting issue: