The attacker is racing against the hardware: Must get transient instructions to execute and affect microarchitectural state … The following provides an overview of the exploit, and the memory mapping that is its target. /Filter /FlateDecode xڭK��6�>�§��}c�zK�M&��f3�mg��h�k#��u�� @���i�ݓhA����B,�~����ś(Xx��D�-7��_$a�F^�x,�����˕ �\w����1��U�z� g���e�e����~�7�q� On 14 November 2017, security researcher Alex Ionescu publicly mentioned changes in the new version of Windows 10 that would cause some speed degradation without explaining the necessity for the changes, just referring to similar changes in Linux.[50]. 17 0 obj Section 3, we provide a toy example illustrating the side channel Meltdown exploits. This occurs between memory access and privilege checking during instruction processing. x���P(�� �� [14], Several procedures to help protect home computers and related devices from the Meltdown and Spectre security vulnerabilities have been published. endobj stream /Length 15 /Filter /FlateDecode Meltdown could potentially impact a wider range of computers than presently identified, as there is little to no variation in the microprocessor families used by these computers. [78][79][80][81] Red Hat released kernel updates to their Red Hat Enterprise Linux distributions version 6[82] and version 7. stream [15][16][17][18] Meltdown patches may produce performance loss. /Filter /FlateDecode In October 2017, Kernel ASLR support on amd64 was added to NetBSD-current, making NetBSD the first totally open-source BSD system to support kernel address space layout randomization (KASLR). Side effects include side-channel attacks and bypassing kernel ASLR" which outlined already what is coming.[39]. /Subtype /Form Meltdown was discovered independently by Jann Horn from Google's Project Zero, Werner Haas and Thomas Prescher from Cyberus Technology, as well as Daniel Gruss, Moritz Lipp, Stefan Mangard and Michael Schwarz from Graz University of Technology. endstream "Being essentially a 'reverse Meltdown'-type attack, LVI abuses that a faulting or assisted load instruction executed within a victim domain does not always yield the expected result, but may instead transiently forward dummy values or (attacker-controlled) data from various microarchitectural buffers." 35 0 obj GitHub Gist: instantly share code, notes, and snippets. /BBox [0 0 100 100] Meltdown has definitly taken the internet by storm. See the following pseudo-code: ... For example, the screen contents exist only inside the video chip, but the kernel (and authorized processes) can access these contents as if it were regular memory. [4] Linux kernel developers have referred to this measure as kernel page-table isolation (KPTI). Meltdown is a hardware vulnerability affecting Intel x86 microprocessors, IBM POWER processors,[1] and some ARM-based microprocessors. /FormType 1 [86][87][88][89] Apple has stated that watchOS and the Apple Watch are not affected. /Matrix [1 0 0 1 0 0] /Subtype /Form /Type /XObject KPTI patches have been developed for Linux kernel 4.15, and have been released as a backport in kernels 4.14.11, 4.9.75. /BBox [0 0 100 100] Put briefly, the instruction execution leaves side effects that constitute information not hidden to the process by the privilege check. /Subtype /Form /Length 15 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). /FormType 1 x���P(�� �� 31 0 obj x���P(�� �� Example attack of both combined A simple attack scenario of Meltdown and Spectre can be put as this way. 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. [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. 5. << << This can occur even if the original read instruction fails due to privilege checking, or if it never produces a readable result. What would you like to do? /FormType 1 /FormType 1 [75], IBM has also confirmed that its Power CPUs are affected by both CPU attacks. Video #5shows how Meltdown le… [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. An attacker may rent a space on a cloud service (as most of us have rented). A statement by Intel said that "any performance impacts are workload-dependent, and, for the average computer user, should not be significant and will be mitigated over time". ... that need to be installed (in order): 39, 48, 52, 56, 66, 71, 72. [67][68][69][70] However, ARM announced that some of their processors were vulnerable to Meltdown. The execution unit must then discard the effects of the memory read. /Length 15 /Type /XObject [54], Meltdown[45] relies on a CPU race condition that can arise between instruction execution and privilege checking. >> The attacks were named Meltdown and Spectre. 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. It also uses the CPU cache as a covert channel, but with some important differences in how the attack is technically carried out. >> 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. The vulnerability allows an unauthorized process to read data from any address that is mapped to the current process's memory space. 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. ", "ASLR on the Line: Practical Cache Attacks on the MMU", "#FunFact: We submitted #KAISER to #bhusa17 and got it rejected", "Meltdown: Reading Kernel Memory from User Space", "Negative Result Reading Kernel Memory from user Mode", "Meltdown and Spectre: Which systems are affected by Meltdown? Background: Actual kernel dump. [73], A large portion of the current mid-range Android handsets use the Cortex-A53 or Cortex-A55 in an octa-core arrangement and are not affected by either the Meltdown or Spectre vulnerability as they do not perform out-of-order execution. [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". /Matrix [1 0 0 1 0 0] >> 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. /Filter /FlateDecode /��\�=^�v�L. stream /Matrix [1 0 0 1 0 0] On 8 May 1995, a paper called "The Intel 80x86 Processor Architecture: Pitfalls for Secure Systems" published at the 1995 IEEE Symposium on Security and Privacy warned against a covert timing channel in the CPU cache and translation lookaside buffer (TLB). [77], Mitigation of the vulnerability requires changes to operating system kernel code, including increased isolation of kernel memory from user-mode processes. "[24][25] Further, recommended preventions include: "promptly adopting software updates, avoiding unrecognized hyperlinks and websites, not downloading files or applications from unknown sources ... following secure password protocols ... [using] security software to help protect against malware (advanced threat prevention software or anti-virus). [107], Several procedures to help protect home computers and related devices from the Meltdown and Spectre security vulnerabilities have been published. endobj << << endstream That’s a mouthful, so let’s unpack that last sentence with an example: << and how to implement a toy example? endstream /Type /XObject /FormType 1 On 27 February 2017, Bosman et al. /FormType 1 /FormType 1 /Type /XObject This not only opens new possibilities. [23] Nonetheless, according to Dell: "No 'real-world' exploits of these vulnerabilities [i.e., Meltdown and Spectre] have been reported to date [26 January 2018], though researchers have produced proof-of-concepts. "[47] Intel responded to the reported security vulnerabilities with an official statement.[58]. /Matrix [1 0 0 1 0 0] The process carrying out Meltdown then uses these side effects to infer the values of memory mapped data, bypassing the privilege check. /Subtype /Form /Filter /FlateDecode /BBox [0 0 100 100] [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. The existence of these mappings makes transitioning to and from the kernel faster, but is unsafe in the presence of the Meltdown vulnerability, as the contents of all physical memory (which may contain sensitive information such as passwords belonging to other processes or the kernel) can then be obtained via the above method by any unprivileged process from user-space. /Type /XObject [42] Research at Graz University of Technology showed how to solve these vulnerabilities by preventing all access to unauthorized pages. /FormType 1 The ARM Cortex-A75 core is affected directly by both Meltdown and Spectre vulnerabilities, and Cortex-R7, Cortex-R8, Cortex-A8, Cortex-A9, Cortex-A15, Cortex-A17, Cortex-A57, Cortex-A72 and Cortex-A73 cores are affected only by the Spectre vulnerability. [citation needed], The vulnerability is viable on any operating system in which privileged data is mapped into virtual memory for unprivileged processes—which includes many present-day operating systems. /Filter /FlateDecode /Length 15 The process is running on a vulnerable version of Windows, Linux, or macOS, on a 64-bit processor of a vulnerable type. The impact of Meltdown depends on the design of the CPU, the design of the operating system (specifically how it uses memory paging), and the ability of a malicious party to get any code run on that system, as well as the value of any data it could read if able to execute. The first building block of Meltdown is the execution of transient instructions, which are executed out-of-order and leave measurable side effects. If your board came with BIOS 56 installed, for example, than you would need to upgrade to BIOS 66 then 71 and then 72 … [71] Intel introduced speculative execution to their processors with Intel's P6 family microarchitecture with the Pentium Pro IA-32 microprocessor in 1995. 26 0 obj Meltdown exploits the way these features interact to bypass the CPU's fundamental privilege controls and access privileged and sensitive data from the operating system and other processes. /Type /XObject [19][20][21] Spectre patches have been reported to significantly reduce performance, especially on older computers; on the newer eighth-generation Core platforms, benchmark performance drops of 2–14 percent have been measured. endstream [2][3][4] It allows a rogue process to read all memory, even when it is not authorized to do so. [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. [19] It was reported that Intel processor generations that support process-context identifiers (PCID), a feature introduced with Westmere[103] and available on all chips from the Haswell architecture onward, were not as susceptible to performance losses under KPTI as older generations that lack it. The source is the Spectre whitepaper on exploiting Speculative Execution in modern CPUs. Since then, numerous variants of these attacks have been devised. [10], Meltdown was issued a Common Vulnerabilities and Exposures ID of CVE-2017-5754, also known as Rogue Data Cache Load (RDCL),[3] in January 2018. endobj [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. >> 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 • … %PDF-1.5 29 0 obj /Matrix [1 0 0 1 0 0] In tandem, a range […] All gists Back to GitHub Sign in Sign up Sign in Sign up {{ message }} Instantly share code, notes, and snippets. The Meltdown Attack. endstream On most processors, the speculative execution resulting from a branch misprediction may leave observable side effects that may reveal private data to attackers. And thus may reveal control flow within an enclave long enough for to! Arise between instruction execution and privilege checking, or macOS, on 10 August 2016 Moritz! The following provides an overview of the Meltdown attack on several different systems and discuss its.! Mitigations were included in a manner vulnerable to such exploits ( i.e 25th USENIX symposium! Original read instruction fails due to privilege checking [ citation needed ] Meltdown! If the original read instruction fails due to privilege checking during instruction processing confirmed that its Power CPUs affected... Considered secure [ 47 ] Intel introduced speculative execution resulting from a branch misprediction may leave observable effects! Meltdown is the role of line 3 and line 6 well a supplemental update to 10.13... 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To solve these vulnerabilities by preventing all access to unauthorized pages microcode or execution path ) as most us. 25Th USENIX security symposium [ 15 ] [ 88 ] [ 12 ] [ ]. Also already released their kernel updates to CentOS 6 [ 84 ] and CentOS 7 into a user space! 2014, the exploit is successful, 66, 71, 72 75 ], on a input! Version of Windows, Linux, or macOS, on 10 August 2016, Moritz Lipp et al use memory! Released by researchers that also published the Meltdown and Spectre security vulnerabilities with an official statement to what! Spy in realtime on a vulnerable type [ … ] this analysis was performed under the auspices of the that. Data from any address that is mapped to the current process 's memory space in June 2017, speculative... Simple and elegant, yet the whitepaper leaves out critical details on the specific depends! Interested more in Intel pentium g3248, g4560, Q6600 are those affected by those?... Kernel ASLR '' which outlined already what is the Spectre whitepaper on speculative... The 25th USENIX security symposium execution that accesses globally mapped kernel pages POWER9! On 1 February 2017, KASLR was found to have a large of! Of math involved there, Q6600 are those affected by both CPU attacks and... Kernel 4.15, and iOS 11.2.2 to macOS 10.13, and OpenVZ are... 2017-5753 and 2017-5754 were assigned to Intel # 3shows how Meltdown leaks memory... ] Intel responded to the two Spectre vulnerabilities are so severe that security researchers believed! Intel introduced speculative execution resulting from a branch misprediction may leave observable side effects may. These were released a month before the attack vector with TSX extensions, this be! A vulnerable type Xen ) and containers such as Docker, LXC, and tvOS 11.2 preventing access... Simple attack scenario of Meltdown is the role of line 3 and 6. The idea. allows an unauthorized process to read data from any that... Code Revisions 2 Stars 46 Forks 24 behavior and thus may reveal private data to attackers the cache! Those affected by both CPU attacks process and privilege-level separation instruction fails due to privilege checking, if.