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In cryptography, a timing attack is a side-channel attack in which the attacker attempts to compromise a cryptosystem by analyzing the time taken to execute cryptographic algorithms. Every logical operation in a computer takes time to execute, and the time can differ based on the input; with precise measurements of the time for each operation, an attacker can work backwards to the input. Finding secrets through timing information may be significantly easier than using cryptanalysis of known plaintext, ciphertext pairs. Sometimes timing information is combined with cryptanalysis to increase the rate of information leakage.
In computer security, a side-channel attack is any attack based on extra information that can be gathered because of the fundamental way a computer protocol or algorithm is implemented, rather than flaws in the design of the protocol or algorithm itself or minor, but potentially devastating, mistakes or oversights in the implementation. Timing information, power consumption, electromagnetic leaks, and sound are examples of extra information which could be exploited to facilitate side-channel attacks.
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core, which stores copies of the data from frequently used main memory locations. Most CPUs have a hierarchy of multiple cache levels, with different instruction-specific and data-specific caches at level 1. The cache memory is typically implemented with static random-access memory (SRAM), in modern CPUs by far the largest part of them by chip area, but SRAM is not always used for all levels, or even any level, sometimes some latter or all levels are implemented with eDRAM.
Prefetching in computer science is a technique for speeding up fetch operations by beginning a fetch operation whose result is expected to be needed soon. Usually this is before it is known to be needed, so there is a risk of wasting time by prefetching data that will not be used. The technique can be applied in several circumstances:
In computer security, a cold boot attack is a type of side channel attack in which an attacker with physical access to a computer performs a memory dump of a computer's random-access memory (RAM) by performing a hard reset of the target machine. Typically, cold boot attacks are used for retrieving encryption keys from a running operating system for malicious or criminal investigative reasons. The attack relies on the data remanence property of DRAM and SRAM to retrieve memory contents that remain readable in the seconds to minutes following a power switch-off.
TRESOR is a Linux kernel patch which provides encryption using only the CPU to defend against cold boot attacks on computer systems by performing encryption inside CPU registers rather than random-access memory (RAM). It is one of two proposed solutions for general-purpose computers. The other, called "frozen cache" uses the CPU cache instead. It was developed from its predecessor AESSE, presented at EuroSec 2010 and presented at USENIX Security 2011. The authors state that it allows RAM to be treated as untrusted from a security viewpoint without hindering the system.
PrivateCore is a venture-backed startup located in Palo Alto, California that develops software to secure server data through server attestation and memory encryption. The company's attestation and memory encryption technology fills a gap that exists between “data in motion” encryption and “data at rest” encryption by protecting “data in use”. PrivateCore memory encryption technology protects against threats to servers such as cold boot attacks, hardware advanced persistent threats, rootkits/bootkits, computer hardware supply chain attacks, and physical threats to servers from insiders. PrivateCore was acquired by Facebook on 7 August 2014.
Datain use is an information technology term referring to active data which is stored in a non-persistent digital state typically in computer random-access memory (RAM), CPU caches, or CPU registers.
Intel Software Guard Extensions (SGX) is a set of instruction codes implementing trusted execution environment that are built into some Intel central processing units (CPUs). They allow user-level and operating system code to define protected private regions of memory, called enclaves. 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.
In cryptography, electromagnetic attacks are side-channel attacks performed by measuring the electromagnetic radiation emitted from a device and performing signal analysis on it. These attacks are a more specific type of what is sometimes referred to as Van Eck phreaking, with the intention to capture encryption keys. Electromagnetic attacks are typically non-invasive and passive, meaning that these attacks are able to be performed by observing the normal functioning of the target device without causing physical damage. However, an attacker may get a better signal with less noise by depackaging the chip and collecting the signal closer to the source. These attacks are successful against cryptographic implementations that perform different operations based on the data currently being processed, such as the square-and-multiply implementation of RSA. Different operations emit different amounts of radiation and an electromagnetic trace of encryption may show the exact operations being performed, allowing an attacker to retrieve full or partial private keys.
Cache prefetching is a technique used by computer processors to boost execution performance by fetching instructions or data from their original storage in slower memory to a faster local memory before it is actually needed. Most modern computer processors have fast and local cache memory in which prefetched data is held until it is required. The source for the prefetch operation is usually main memory. Because of their design, accessing cache memories is typically much faster than accessing main memory, so prefetching data and then accessing it from caches is usually many orders of magnitude faster than accessing it directly from main memory. Prefetching can be done with non-blocking cache control instructions.
Hardware backdoors are backdoors in hardware, such as code inside hardware or firmware of computer chips. The backdoors may be directly implemented as hardware Trojans in the integrated circuit.
Meltdown is one of the two original transient execution CPU vulnerabilities. Meltdown affects 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 one of the two original transient execution CPU vulnerabilities, which involve 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.
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 archetype is Spectre, and transient execution attacks like Spectre belong to the cache-attack category, one of several categories of side-channel attacks. Since January 2018 many different cache-attack vulnerabilities have been identified.
Apple M1 is a series of ARM-based system-on-a-chip (SoC) designed by Apple Inc. as a central processing unit (CPU) and graphics processing unit (GPU) for its Mac 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 Worldwide Developers Conference (WWDC).
Pacman is a side-channel vulnerability in certain ARM CPUs that was made public by Massachusetts Institute of Technology security researchers on June 10, 2021. It affects the pointer authentication (PAC) mechanism in many ARMv8.3 chips, including Apple's M1 CPU. Pacman creates an 'oracle' that lets an attacker guess a pointer's PAC signature without crashing the program if the guess is wrong. PAC signatures are typically less than 16 bits wide, so an attacker can use the oracle to guess the signature in 216 tries or fewer. It is unfixable without hardware changes because it is caused by the inherent design of CPU caches and branch predictors.
Hertzbleed is a hardware security attack which describes exploiting dynamic frequency scaling to reveal secret data. The attack is a kind of timing attack, bearing similarity to previous power analysis vulnerabilities. Hertzbleed is more dangerous than power analysis, as it can be exploited by a remote attacker. Disclosure of cryptographic keys is the main concern regarding the exploit but other uses of the attack have been demonstrated since its initial discovery.
Confidential computing is a security and privacy-enhancing computational technique focused on protecting data in use. Confidential computing can be used in conjunction with storage and network encryption, which protect data at rest and data in transit respectively. It is designed to address software, protocol, cryptographic, and basic physical and supply-chain attacks, although some critics have demonstrated architectural and side-channel attacks effective against the technology.
GoFetch is a family of cryptographic attacks on recent Apple silicon CPUs that exploits the CPU's on-chip data memory-dependent prefetcher (DMP) to investigate the contents of memory. CPUs affected include the M1, M2, M3 and A14 series system-on-a-chip processors.
References
- ↑ "Augury: Using Data Memory-Dependent Prefetchers to Leak Data at Rest". www.prefetchers.info. 2022-05-02. Retrieved 2024-03-30.
- ↑ Vicarte, Jose Rodrigo Sanchez; Flanders, Michael; Paccagnella, Riccardo; Garrett-Grossman, Grant; Morrison, Adam; Fletcher, Christopher W.; Kohlbrenner, David (May 2022). Augury: Using Data Memory-Dependent Prefetchers to Leak Data at Rest. 2022 IEEE Symposium on Security and Privacy (SP). San Francisco, CA, USA: IEEE. pp. 1491–1505. doi:10.1109/SP46214.2022.9833570. ISBN 978-1-6654-1316-9.
- ↑ Bakhshalipour, Mohammad; Shakerinava, Mehran; Golshan, Fatemeh; Ansari, Ali; Lotfi-Karman, Pejman; Sarbazi-Azad, Hamid (2020-09-01). "A Survey on Recent Hardware Data Prefetching Approaches with An Emphasis on Servers". arXiv: 2009.00715 [cs.AR].
- ↑ Goodin, Dan (2024-03-21). "Unpatchable vulnerability in Apple chip leaks secret encryption keys". Ars Technica. Retrieved 2024-03-21.
- ↑ "Apple Silicon chip flaw can leak encryption keys, say researchers". AppleInsider. 2024-03-21. Retrieved 2024-03-22.
- 1 2 "GoFetch: Breaking Constant-Time Cryptographic Implementations Using Data Memory-Dependent Prefetchers". gofetch.fail. Retrieved 2024-03-22.
- ↑ "Data Dependent Prefetcher". Intel. Retrieved 2024-03-21.
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