Last active Mar 4, 2019. /Subtype /Form /Type /XObject Meltdown was published simultaneously with the Spectre Attack, which exploits a different CPU performance feature, called speculative execution, to leak confidential information. 20 0 obj /Length 15 Above example was an instance of dynamic scheduling. /Resources 27 0 R The execution unit must then discard the effects of the memory read. This article is about how it actually works — you can read more about the implications of these vulnerabilities at the Meltdown site and elsewhere. [104][105] This is because the selective translation lookaside buffer (TLB) flushing enabled by PCID (also called address space number or ASN under the Alpha architecture) enables the shared TLB behavior crucial to the exploit to be isolated across processes, without constantly flushing the entire cache – the primary reason for the cost of mitigation. a software-based solution) or avoidance of the underlying race condition (i.e. /Subtype /Form stream Instructions execute speculatively out of order, but . Within the scope of research we were able to implement a proof-of-concept that is able to reliably dump kernel memory from arbitrary addresses: Foreground: Kernel memory being read out by our meltdown proof-of-concept. endstream [20][62][63][64] When the effect of Meltdown was first made public Intel countered that the flaws affect all processors,[65] but AMD denied this, saying "we believe AMD processors are not susceptible due to our use of privilege level protections within paging architecture". /Type /XObject On 9 January 2018, Microsoft paused the distribution of the update to systems with affected CPUs while it investigates and addresses this bug.[100]. what makes this attack special? Executing transient instructions. (Ok, it is a bit more complicated than that because of GPUs, but you get the idea.) /Type /XObject In practice, because cache side-channel attacks are slow, it's faster to extract data one bit at a time (only 2 × 8 = 16 cache attacks needed to read a byte, rather than 256 steps if it tried to read all 8 bits at once). For example, before kernel page-table isolation was introduced, most versions of Linux mapped all physical memory into the address space of every user-space process; the mapped addresses are (mostly) protected, making them unreadable from user-space and accessible only when transitioned into the kernel. [11][12][13] The vulnerabilities are so severe that security researchers initially believed the reports to be false. Video #2shows how Meltdown leaks physical memory content. [27][28][29][30] On 8 October 2018, Intel is reported to have added hardware and firmware mitigations regarding Spectre and Meltdown vulnerabilities to its latest processors. "[24][25], On 25 January 2018, the current status and possible future considerations in solving the Meltdown and Spectre vulnerabilities were presented. endobj endstream Be sure and read the questions Wall Street should have asked", "Intel processors are being redesigned to protect against Spectre – New hardware coming later this year", "Intel will block Spectre attacks with new chips this year – Cascade Lake processors for servers, coming this year, will fight back against a new class of vulnerabilities, says CEO Brian Krzanich", "Intel Publishes Spectre & Meltdown Hardware Plans: Fixed Gear Later This Year", "Intel announces hardware fixes for Spectre and Meltdown on upcoming chips", "Intel's New Core and Xeon W-3175X Processors: Spectre and Meltdown Security Update", "What Are the Spectre and Meltdown CPU Vulnerabilities", "The Intel 80x86 Processor Architecture: Pitfalls for Secure Systems", "OS X Mountain Lion Core Technologies Overview", "Blackhat USA 2016, Using Undocumented CPU Behavior to See into Kernel Mode and Break KASLR in the Process", "ARMageddon: Cache Attacks on Mobile Devices", "What could possibly go wrong with ? 5. >> /Length 15 Spectre and Meltdown are security flaws, recently and independently discovered by researchers at Google Project Zero and other organizations [] [] [].The originality of the Meltdown and Spectre attacks is that they exploit security vulnerabilities in the microarchitecture of modern microprocessors, even if the microprocessors have … The vulnerabilities were mitigated by a new partitioning system that improves process and privilege-level separation. [54], Meltdown[45] relies on a CPU race condition that can arise between instruction execution and privilege checking. This repository contains several videos demonstrating Meltdown 1. [22] On 18 January 2018, unwanted reboots, even for newer Intel chips, due to Meltdown and Spectre patches, were reported. [100][101][102] The update was found to have caused issues on systems running certain AMD CPUs, with some users reporting that their Windows installations did not boot at all after installation. << [107], Several procedures to help protect home computers and related devices from the Meltdown and Spectre security vulnerabilities have been published. /Type /XObject [67][68][69][70] However, ARM announced that some of their processors were vulnerable to Meltdown. Meltdown has definitly taken the internet by storm. [21][20] Phoronix benchmarked several popular PC games on a Linux system with Intel's Coffee Lake Core i7-8700K CPU and KPTI patches installed, and found that any performance impact was little to non-existent. /Resources 36 0 R [37], On 10 August 2016, Moritz Lipp et al. >> 26 0 obj [48] However, the partially open-source[49] Apple Darwin, which forms the foundation of macOS and iOS (among others), is based on FreeBSD; KASLR was added to its XNU kernel in 2012 as noted above. Since then, numerous variants of these attacks have been devised. /Filter /FlateDecode /BBox [0 0 100 100] [42] Research at Graz University of Technology showed how to solve these vulnerabilities by preventing all access to unauthorized pages. Defenses against Meltdown would require avoiding the use of memory mapping in a manner vulnerable to such exploits (i.e. /FormType 1 The attack seems quite simple and elegant, yet the whitepaper leaves out critical details on the specific vulnerability. %���� stream 11 0 obj << /Resources 18 0 R [85], Apple included mitigations in macOS 10.13.2, iOS 11.2, and tvOS 11.2. /Filter /FlateDecode They also attempted but failed to exploit CPU operations for memory alignment, division by zero, supervisor modes, segment limits, invalid opcodes, and non-executable code. [26], On 15 March 2018, Intel reported that it will redesign its CPU processors to help protect against the Meltdown and related Spectre vulnerabilities (especially, Meltdown and Spectre-V2, but not Spectre-V1), and expects to release the newly redesigned processors later in 2018. /Subtype /Form [34] This analysis was performed under the auspices of the National Security Agency's Trusted Products Evaluation Program (TPEP). 8 Exploiting modern microarchitectures: Meltdown, Spectre, and other attacks Examples of computer architectures • Intel “x86” (Intel x64/AMD64) • CISC (Complex Instruction Set Computer) • Variable width instructions (up to 15 bytes) • 16 GPRs (General Purpose Registers) • Can operate directly on memory • 64-bit flat virtual address space • “Canonical” 48/56-bit addressing • Upper half kernel, Lower half user • … /Resources 8 0 R /Resources 21 0 R /Matrix [1 0 0 1 0 0] [44] Nevertheless, this work led to kernel page-table isolation (KPTI, originally known as KAISER) in 2017, which was confirmed to eliminate a large class of security bugs, including some limited protection against the not-yet-discovered Meltdown – a fact confirmed by the Meltdown authors. In July 2012, Apple's XNU kernel (used in macOS, iOS and tvOS, among others) adopted kernel address space layout randomization (KASLR) with the release of OS X Mountain Lion 10.8. << [38], On 27 December 2016, at 33C3, Clémentine Maurice and Moritz Lipp of TU Graz presented their talk "What could possibly go wrong with ? endobj 7 0 obj 3 for known Meltdown-style attacks in processors with in-order pipelines. endobj /Subtype /Form Meltdown is distinct from Spectre in several ways, notably that Spectre requires tailoring to the victim process’s software environment but applies more broadly to CPUs and is not mitigated by KAISER. A purely software workaround to Meltdown has been assessed as slowing computers between 5 and 30 percent in certain specialized workloads,[9] although companies responsible for software correction of the exploit are reporting minimal impact from general benchmark testing. Accordingly, many servers and cloud services were impacted,[8] as well as a potential majority of smart devices and embedded devices using ARM based processors (mobile devices, smart TVs, printers and others), including a wide range of networking equipment. 31 0 obj << /Matrix [1 0 0 1 0 0] << After affected hardware and software vendors had been made aware of the issue on 28 July 2017,[51] the two vulnerabilities were made public jointly, on 3 January 2018, several days ahead of the coordinated release date of 9 January 2018 as news sites started reporting about commits to the Linux kernel and mails to its mailing list. The Meltdown flaw breaks the isolation between user applications and the operating system , allowing the attack to gain access to system memory and other applications in the OS. /FormType 1 Meltdown demonstrates that out-of-order execution can leak kernel memory into user mode long enough for it to be captured by a side-channel cache attack. /Resources 12 0 R [66], Researchers have indicated that the Meltdown vulnerability is exclusive to Intel processors, while the Spectre vulnerability can possibly affect some Intel, AMD, and ARM processors. >> This transient execution attack is called Load Value Injection (LVI) and is an example of a … On most processors, the speculative execution resulting from a branch misprediction may leave observable side effects that may reveal private data to attackers. Additionally, combined with a cache side-channel attack, this vulnerability allows a process to bypass the normal privilege checks that isolate the exploit process from accessing data belonging to the operating system and other running processes. Meltdown's proof-of-concept released by researchers that also published the meltdown paper. /Type /XObject x���P(�� �� In July 2017, research made public on the CyberWTF website by security researcher Anders Fogh outlined the use of a cache timing attack to read kernel space data by observing the results of speculative operations conditioned on data fetched with invalid privileges.[46]. /Type /XObject Modern computer processors use a variety of techniques to gain high levels of efficiency. Google's "Project ZERO" shows a concrete example of attack and said that the success rate was 99%, but the condition is "using two VMs on KVM, using Intel Hyper-Threading, Dedicated assignment of one identical physical core divided into two logical cores "," Invalidate ASLR for both VMs "," Run the same malicious program with the same memory address in two VMs "The program is a story in an … x���P(�� �� stream endstream /FormType 1 Meltdown affects a wide range of systems. stream What is the role of line 3 and line 6? stream [31], In November 2018, two new variants of the attacks were revealed. [15][16][17][18] Meltdown patches may produce performance loss. One of those effects, however, can be caching of the data at Base+A, which may have been completed as a side effect of the memory access, This page was last edited on 19 December 2020, at 04:38. If the environment is vulnerable, the attacker may capture sensitive information of other customers in the same environment, which is of course, scary! [63] In other tests, including synthetic I/O benchmarks and databases such as PostgreSQL and Redis, an impact in performance was found, accounting even to tens of percents for some workloads. The Meltdown attack is a cunning way of bypassing the security checks of many modern CPUs and allows reading kernel mode memory from any process on un-patched operating systems. << /BBox [0 0 100 100] An article explaining the SPectre and Meltdown attacks. [36], On 8 August 2016, Anders Fogh and Daniel Gruss presented "Using Undocumented CPU Behavior to See Into Kernel Mode and Break KASLR in the Process" at the Black Hat 2016 conference. Background: Actual kernel dump. It was reported that implementation of KPTI may lead to a reduction in CPU performance, with some researchers claiming up to 30% loss in performance, depending on usage, though Intel considered this to be an exaggeration. [40], On 27 March 2017, researchers at Austria's Graz University of Technology developed a proof-of-concept that could grab RSA keys from Intel SGX enclaves running on the same system within five minutes by using certain CPU instructions in lieu of a fine-grained timer to exploit cache DRAM side-channels. x���P(�� �� This example shows that a Meltdown-style attack can be based on even subtler side effects than those resulting from out-of-order execution. Branch Target Injection (Spectre, Variant 2), Rogue Data Cache Load (Meltdown, Variant 3), Rogue System Register Read (Spectre-NG, Variant 3a), Speculative Store Bypass (Spectre-NG, Variant 4), Office of Personnel Management data breach, Hollywood Presbyterian Medical Center ransomware incident, Democratic National Committee cyber attacks, Russian interference in the 2016 U.S. elections, https://en.wikipedia.org/w/index.php?title=Meltdown_(security_vulnerability)&oldid=995090275, Speculative execution security vulnerabilities, Short description is different from Wikidata, Articles with unsourced statements from November 2020, Articles needing cleanup from January 2018, Articles with sections that need to be turned into prose from January 2018, Articles lacking reliable references from January 2018, Creative Commons Attribution-ShareAlike License, New CPU instructions eliminating branch speculation, The CPU attempts to execute an instruction referencing a memory operand. 3. [23] According to Dell: "No 'real-world' exploits of these vulnerabilities [ie, Meltdown and Spectre] have been reported to date [26 January 2018], though researchers have produced proof-of-concepts. [43] A presentation on the resulting KAISER technique was submitted for the Black Hat congress in July 2017, but was rejected by the organizers. /Resources 34 0 R 29 0 obj It also uses the CPU cache as a covert channel, but with some important differences in how the attack is technically carried out. [citation needed], Since many operating systems map physical memory, kernel processes, and other running user space processes into the address space of every process, Meltdown effectively makes it possible for a rogue process to read any physical, kernel or other processes' mapped memory—regardless of whether it should be able to do so. [35], In March 2014, the Linux kernel adopted KASLR to mitigate address leaks. stream /Length 15 /Filter /FlateDecode These were released a month before the vulnerabilities were made public.
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