Intel L1 Terminal Fault Vulnerabilities – VxRail fix

So Dell EMC have finally released an update to VxRail that fixes the Intel vulnerability which Intel disclosed last month…. Software version 4.0.520 and 4.5.218….

I know a lot of customers have been asking why it’s taken so long, but they have to understand that the VxRail is a turnkey appliance which means Dell EMC and VMware do a whole bunch of testing and validation to ensure any patches/upgrades do not impact the end-user. VxRail’s update process is fully automated and the validation ensures that end-users can be reassured that when they upload the update file and hit ‘install’ that they will go from one good known state to another!


VxRail Appliance software 4.0.520 contains vSphere 6.0 Express Patch 15 / Upgrade
3h which addresses the L1 Terminal Fault vulnerability.

VxRail 4.5.218 contains vSphere 6.5 EP8/U2c which addresses the L1 Terminal Fault vulnerability.

Refer to VMware KB reference 55636 for a centralized source of information. A high-level introduction follows:

  • CVE-2018-3646 (L1 Terminal Fault – VMM), requires Hypervisor-Specific Mitigations for hosts running on Intel hardware.
    • Sequential-Context attack vector: mitigated through a vSphere update process including vCenter and ESXi. Mitigation enabled by default and does not impose a significant performance impact.
    • Concurrent-context attack vector: mitigated by enabling a new advanced configuration option hyperthreading Mitigation included in the update. This option also known as the ESXi Side-Channel-Aware Scheduler. The initial version of this feature will only schedule the hypervisor and VMs on one logical process of an Intel Hyperthreading-enabled core. This feature may impose a non-trivial performance impact and is not enabled by default. Please take time to analyze your environment’s capacity prior to enabling the mitigation.
    • For technical details please see VMware KB reference 55806.
  • CVE-2018-3620 (L1 Terminal Fault – OS)
    • Local privilege escalation, requires Operating System-Specific Mitigations. vCSA (and PSC) 6.x are impacted, workaround is available.
    • For technical details please see VMware Security Bulletin VMSA-2018-0021, VMware KB reference 55807 and 52312.
  • CVE-2018-3615 (L1 Terminal Fault – SGX)
    • Does not affect VxRail and VMware products. See VMware KB reference 54913.


Upgrades should be available to download and run…. Alternatively speak to your Dell EMC representative (or contact me or my company: MTI)


MTI Secure Hyper-Converged Infrastructure Webinar & Guide

Back end of February I presented a webinar with my colleague, Andrew Tang, around Key Challenges and Considerations for Securing Hyper-Converged Infrastructure.

The webinar has been uploaded for public consumption by the marketing team at MTI Technology.

As I mentioned previously in my blog, I don’t really touch upon product in this webinar as the last thing customers want is to be shoehorned into a certain vendor product… instead I hope the webinar gives enough information about what HCI is in general, why customers should be looking at HCI during their next infrastructure refresh, and more importantly what to consider when evaluating a HCI solution!

You can access the webinar recording here: (sorry, you have to fill in your details to gain access….)

Marketing has also finally released the HCI guide that both Andrew and myself put together around HCI, feel free to download that here:

Finally, if you’re interested in talking more about HCI then feel free to contact me or register for one of MTI’s HCI Discovery Workshops:

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