Meltdown & Spectre: How to protect yourself from these CPU security flaws

The first few days of 2018 have been filled with anxious discussions concerning a widespread and wide-ranging vulnerability in the architecture of processors based on Intel’s Core architecture used in PCs for many years, and also affecting ARM processors commonly used in tablets and smartphones.

According to Google’s research division, Project Zero, the flaws affect the microprocessors in the majority of the world’s computers, including mobile devices and cloud networks, and can allow hackers to access the entire contents of a computer’s memory.

The good news is that ESET can help protect against the types of malware that could take advantage of these vulnerabilities.

And, ESET was one of the very first security vendors to allow the Microsoft patch against the flaw to be enabled.

While ESET protects against potential malware infection, you should also take these steps to secure your computers and data:

  1. Make sure your browser is up to date. For Chrome or Firefox users:
  • Mozilla has released information describing their response, including how Firefox 57 will address these security flaws.
  • Google has stated, “Chrome 64, due to be released January 23, will contain mitigations to protect against exploitation.” In the meantime, you can enable “Site Isolation” found in current stable versions of Chrome to provide better protection.
  1. Make sure you update your ESET software, then update your Windows OS to protect against this exploit. To update ESET:
  • ESET Home products (NOD32 Antivirus, Internet Security, Smart Security Premium)
  • ESET Business products (Endpoint Antivirus, Endpoint Security, File and Mail Security and Virtualization Security)
  1. Customers should review ESET’s Knowledgebase article for important updates.
  2. See this great collection of tips, articles and recommendations from the Google Project Zero team.
  3. If you have a cloud-based server or have a website hosted by hosting provider, check to see what mitigations they have implemented already to prevent Meltdown.


At the time of this writing, not all details have been released, but reportedly the issue is that programs running in user-mode address space (the “normal” range of memory in which application software, games and the like run) on a computer can infer or “see ” some of the information stored in kernel-mode address space (the “protected” range of memory used to contain the operating system, its device drivers, and sensitive information such as passwords and cryptography certificates).

Fixes to prevent user-mode programs from “peering inside” kernel-mode memory are being introduced by operating system vendors, hypervisor vendors and even cloud computing companies, but it appears the initial round of patches will slow down operating systems to some extent.

The exact amount of slowdown is open to debate.  Intel has stated the performance penalty will “not be significant” for most users, but Linux enthusiast site Phoronix has benchmarked performance penalties from 5-30%, depending upon what the computer is doing.


A long Reddit thread titled Intel bug incoming has been tracking the vulnerability since information about it began to appear on January 2, 2018; Ars Technica and The Register have had excellent coverage, as well.

Processor manufacturer AMD announced that they are unaffected, according to reports on CNBC and a message to the Linux Kernel Mailing List by an AMD engineer, but reports from both Google‘s Project Zero and Microsoft state that AMD processors are affected, which makes the situation less clear.

The Microsoft article goes on to note that this is not a Windows-specific issue, and that it affects Android, Chrome OS, iOS and macOS as well.

Red Hat‘s advisory includes IBM’s POWER architecture as being vulnerable.  Hypervisor manufacturers VMware and Xen have issued their own advisories, as has as Amazon Web Services.

Affected Vendors

Here is a list of affected vendors and their respective advisories and/or patch announcements:

Vendor Advisory/Announcement
Amazon (AWS) AWS-2018-013: Processor Speculative Execution Research Disclosure
Apple HT208331: About the security content of macOS High Sierra 10.13.2, Security Update 2017-002 Sierra, and Security Update 2017-005 El Capitan
HT208394: About speculative execution vulnerabilities in ARM-based and Intel CPUs
ARM Vulnerability of Speculative Processors to Cache Timing Side-Channel Mechanism
Azure Securing Azure customers from CPU vulnerability
Microsoft Cloud Protections Against Speculative Execution Side-Channel Vulnerabilities
Google’s Project Zero Reading Privileged Memory with a Side-Channel
IBM Potential CPU Security Issue
Intel INTEL-SA-00088 Speculative Execution and Indirect Branch Prediction Side Channel Analysis Method
Microsoft Security Advisory 180002: Guidance to mitigate speculative execution side-channel vulnerabilities
Windows Client guidance for IT Pros to protect against speculative execution side-channel vulnerabilities
Windows Server guidance to protect against speculative execution side-channel vulnerabilities
Important information regarding the Windows security updates released on January 3, 2018 and anti-virus software
Mozilla Mozilla Foundation Security Advisory 2018-01: Speculative execution side-channel attack (“Spectre”)
Red Hat Kernel Side-Channel Attacks – CVE-2017-5754 CVE-2017-5753 CVE-2017-5715
VMware NEW VMSA VMSA-2018-0002 VMware ESXi, Workstation and Fusion updates address side-channel analysis due to speculative execution
Xen Advisory XSA-254: Information leak via side effects of speculative execution

Technical Details

The confusion over brands of affected CPUs may be due to the fact that this is not one vulnerability, but two similar vulnerabilities, dubbed Meltdown and Spectre by their respective discoverers.

These vulnerabilities have three CVE numbers (a quasi-government standard for tracking computer security vulnerabilities and exposures) assigned to them:

CVE Number Description
CVE-2017-5715 Branch Target Injection, exploited by Spectre
CVE-2017-5753 Bounds Check Bypass, exploited by Spectre
CVE-2017-5754 Rogue Data Cache Load, exploited by Meltdown

For many years, processor manufacturers – such as Intel –have been able to fix flaws in processor architecture through microcode updates, which write an update to the processor itself to fix a bug.

For a – so far unannounced – reason or reasons, this vulnerability may not be not fixable this way in Intel processors, so instead, operating system manufacturers have collaborated with Intel to release patches for the vulnerabilities.

Intel’s security advisory, INTEL-SA-00088 Speculative Execution and Indirect Branch Prediction Side Channel Analysis Method, lists forty-four (44) affected families of processors, each of which can contain dozens of models.

ARM Limited has released an advisory titled Vulnerability of Speculative Processors to Cache Timing Side-Channel Mechanism that currently lists ten (10) affected models of processor.

ESET’s Response

As mentioned at the beginning of the article, ESET released Antivirus and Antispyware module update 1533.3 on Wednesday, January 3, 2017, to all customers to ensure compatibility with Microsoft’s updates to the Windows operating systems.

ESET is working alongside hardware and software vendors to mitigate the vulnerabilities posed by the vulnerabilities.

For additional information see:

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Meltdown & Spectre: How to protect yourself from these CPU security flaws