Simultaneous multithreading (SMT) is a technique for improving the overall efficiency of superscalar CPUs with hardware multithreading. SMT permits multiple independent threads of execution to better use the resources provided by modern processor architectures.
RDRAND is an instruction for returning random numbers from an Intel on-chip hardware random number generator which has been seeded by an on-chip entropy source. RDRAND is available in Ivy Bridge processors and is part of the Intel 64 and IA-32 instruction set architectures. AMD added support for the instruction in June 2015.
In computer security, virtual machine escape is the process of a program breaking out of the virtual machine on which it is running and interacting with the host operating system. A virtual machine is a "completely isolated guest operating system installation within a normal host operating system". In 2008, a vulnerability in VMware discovered by Core Security Technologies made VM escape possible on VMware Workstation 6.0.2 and 5.5.4. A fully working exploit labeled Cloudburst was developed by Immunity Inc. for Immunity CANVAS. Cloudburst was presented in Black Hat USA 2009.
The Intel Management Engine (ME), also known as the Intel Manageability Engine, is an autonomous subsystem that has been incorporated in virtually all of Intel's processor chipsets since 2008. It is located in the Platform Controller Hub of modern Intel motherboards.
Row hammer is a security exploit that takes advantage of an unintended and undesirable side effect in dynamic random-access memory (DRAM) in which memory cells interact electrically between themselves by leaking their charges, possibly changing the contents of nearby memory rows that were not addressed in the original memory access. This circumvention of the isolation between DRAM memory cells results from the high cell density in modern DRAM, and can be triggered by specially crafted memory access patterns that rapidly activate the same memory rows numerous times.
Intel Software Guard Extensions (SGX) is a set of security-related instruction codes that are built into some Intel central processing units (CPUs). They allow user-level and operating system code to define private regions of memory, called enclaves, whose contents is inaccessible from the outside. SGX is designed to be useful for implementing secure remote computation, secure web browsing, and digital rights management (DRM). Other applications include concealment of proprietary algorithms and of encryption keys.
Zen is the codename for the first iteration in a family of computer processor microarchitectures of the same name from AMD. It was first used with their Ryzen series of CPUs in February 2017. The first Zen-based preview system was demonstrated at E3 2016, and first substantially detailed at an event hosted a block away from the Intel Developer Forum 2016. The first Zen-based CPUs, codenamed "Summit Ridge", reached the market in early March 2017, Zen-derived Epyc server processors launched in June 2017 and Zen-based APUs arrived in November 2017.
Ryzen is a brand of multi-core x86-64 microprocessors designed and marketed by Advanced Micro Devices (AMD) for desktop, mobile, server, and embedded platforms based on the Zen microarchitecture. It consists of central processing units (CPUs) marketed for mainstream, enthusiast, server, and workstation segments and accelerated processing units (APUs) marketed for mainstream and entry-level segments and embedded systems applications.
EPYC is a brand of multi-core x86-64 microprocessors designed and sold by AMD, based on the company's Zen microarchitecture. Introduced in June 2017, they are specifically targeted for the server and embedded system markets. Epyc processors share the same microarchitecture as their regular desktop-grade counterparts, but have enterprise-grade features such as higher core counts, more PCI Express lanes, support for larger amounts of RAM, and larger cache memory. They also support multi-chip and dual-socket system configurations by using the Infinity Fabric interconnect.
Meltdown is a hardware vulnerability affecting Intel x86 microprocessors, IBM POWER processors, and some ARM-based microprocessors. It allows a rogue process to read all memory, even when it is not authorized to do so.
Spectre is a subset of security vulnerabilities within the class of vulnerabilities known as microarchitectural timing side-channel attacks. These affect modern microprocessors that perform branch prediction and other forms of speculation. On most processors, the speculative execution resulting from a branch misprediction may leave observable side effects that may reveal private data to attackers. For example, if the pattern of memory accesses performed by such speculative execution depends on private data, the resulting state of the data cache constitutes a side channel through which an attacker may be able to extract information about the private data using a timing attack.
The AMD Platform Security Processor (PSP), officially known as AMD Secure Technology, is a trusted execution environment subsystem incorporated since about 2013 into AMD microprocessors. According to an AMD developer's guide, the subsystem is "responsible for creating, monitoring and maintaining the security environment" and "its functions include managing the boot process, initializing various security related mechanisms, and monitoring the system for any suspicious activity or events and implementing an appropriate response". Critics worry it can be used as a backdoor and is a security concern. AMD has denied requests to open source the code that runs on the PSP.
Speculative Store Bypass (SSB) is the name given to a hardware security vulnerability and its exploitation that takes advantage of speculative execution in a similar way to the Meltdown and Spectre security vulnerabilities. It affects the ARM, AMD and Intel families of processors. It was discovered by researchers at Microsoft Security Response Center and Google Project Zero (GPZ). After being leaked on 3 May 2018 as part of a group of eight additional Spectre-class flaws provisionally named Spectre-NG, it was first disclosed to the public as "Variant 4" on 21 May 2018, alongside a related speculative execution vulnerability designated "Variant 3a".
Lazy FPU state leak, also referred to as Lazy FP State Restore or LazyFP, is a security vulnerability affecting Intel Core CPUs. The vulnerability is caused by a combination of flaws in the speculative execution technology present within the affected CPUs and how certain operating systems handle context switching on the floating point unit (FPU). By exploiting this vulnerability, a local process can leak the content of the FPU registers that belong to another process. This vulnerability is related to the Spectre and Meltdown vulnerabilities that were publicly disclosed in January 2018.
Foreshadow, known as L1 Terminal Fault (L1TF) by Intel, is a vulnerability that affects modern microprocessors that was first discovered by two independent teams of researchers in January 2018, but was first disclosed to the public on 14 August 2018. The vulnerability is a speculative execution attack on Intel processors that may result in the disclosure of sensitive information stored in personal computers and third-party clouds. There are two versions: the first version (original/Foreshadow) targets data from SGX enclaves; and the second version (next-generation/Foreshadow-NG) targets virtual machines (VMs), hypervisors (VMM), operating systems (OS) kernel memory, and System Management Mode (SMM) memory. A listing of affected Intel hardware has been posted.
In digital computing, hardware security bugs are hardware bugs or flaws that create vulnerabilities affecting computer central processing units (CPUs), or other devices which incorporate programmable processors or logic and have direct memory access, which allow data to be read by a rogue process when such reading is not authorized. Such vulnerabilities are considered "catastrophic" by security analysts.
The Microarchitectural Data Sampling (MDS) vulnerabilities are a set of weaknesses in Intel x86 microprocessors that use hyper-threading, and leak data across protection boundaries that are architecturally supposed to be secure. The attacks exploiting the vulnerabilities have been labeled Fallout, RIDL, ZombieLoad., and ZombieLoad 2.
Transient execution CPU vulnerabilities are vulnerabilities in a computer system in which a speculative execution optimization implemented in a microprocessor is exploited to leak secret data to an unauthorized party. The classic example is Spectre that gave its name to this kind of side-channel attack, but since January 2018 many different vulnerabilities have been identified.
SWAPGS, also known as Spectre variant 1 (swapgs), is a computer security vulnerability that utilizes the branch prediction used in modern microprocessors. Most processors use a form of speculative execution, this feature allows the processors to make educated guesses about the instructions that will most likely need to be executed in the near future. This speculation can leave traces in the cache, which attackers use to extract data using a timing attack, similar to side-channel exploitation of Spectre.
Apple M1 is a series of ARM-based system-on-a-chips (SoCs) designed by Apple Inc. as a central processing unit (CPU) and graphics processing unit (GPU) for its Macintosh desktops and notebooks, and the iPad Pro and iPad Air tablets. The M1 chip initiated Apple's third change to the instruction set architecture used by Macintosh computers, switching from Intel to Apple silicon 14 years after they were switched from PowerPC to Intel, and 26 years after the transition from the original Motorola 68000 series to PowerPC. At the time of introduction in 2020, Apple said that the M1 had the world's fastest CPU core "in low power silicon" and the world's best CPU performance per watt. Its successor, Apple M2, was announced on June 6, 2022 at WWDC.
Worcester Polytechnic Institute 
University of Lübeck 
