Questions tagged [meltdown]

A side-channel vulnerability affecting Intel x86 and few ARM-based microprocessors allowing user processes to read memory belonging to the kernel. Affects various OSes like Linux, OS X, and Windows. Published in January 2018.

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How would one compare Cache Allocating Technology against MIT's Dynamically Allocated Way Guard for prevention of the Spectre side-channel Attack?

Upon research, I'm finding it difficult to identify a way to compare each solution. Is it correct in saying both solutions are software based? Therefore, could I compare overall PC perfomance with ...
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How risky would it be to run a Linux kernel without Spectre and Meltdown patches on a regular desktop system?

What would happen if we adopted: https://make-linux-fast-again.com/ Assume the system is used for development and general browsing. Are there any cases of these vulnerabilities being exploited in ...
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Application level protection against Meltdown, Spectre, Foreshadow, Fallout. Zombieload

Is it possible to develop an application in such a way that its data in memory cant be stolen by recent attacks such as Meltdown, Spectre, Foreshadow, Fallout. Zombieload? All mitigations focus on ...
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Software mitigation for variant 3a (rogue system register read) and variant 4 (speculative store bypass)

AFAIK, all mitigable meltdown / spectre variants have software mitigation except for variant 3a and 4. Why is this the case? For variant 4, a straightforward software mitigation is to place lfence ...
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Why must Meltdown use probe array?

This is code snippet of Meltdown assembly language code: 1. ; rcx = kernel address, rbx = probe array 2. xor rax, rax 3. retry: 4. mov al, byte [rcx] 5. shl rax, 0xc 6. jz retry 7. mov rbx, ...
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Is Meltdown/Spectre mitigation necessary in virtual machine as well as in hypervisor? [duplicate]

I am running virtual machines in kvm/qemu hypervisor. The hypervisor has Meltdown/Spectre mitigation enabled in kernel. Is it necessary that virtual machines have the Meltdown/Spectre mitigation ...
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Meltdown checker says AWS and Rackspace is vulnerable - Why?

Today I was curious how my vmware environment stacked up against Spectre and Meltdown. So I ran spectre-meltdown-checker. It came back clean with 7 of 8 variants OK (the failed one is apparently ...
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Can someone explain in layman terms how Spectre and Meltdown expose protected data

I'm working on a document about them and I think I understand it general what happens -> by exploiting the CPUs memory caching and speculative execution but I'm a little lost of how protected data is ...
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Mitigation of Spectre and Meltdown affecting host OS from guest OS (Virtualbox)

I don't know all the details of Spectre and Meltdown, but the way I understand it is that they allow reading from memory, not writing to it. Also, I read that at least Spectre can get out of the ...
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Are new AMD processors more secure than Intel ones?

Since the discovery of Meltdown and Spectre, CPU security has been compromised and trust to the main manufacturers reduced, particularly Intel. 8 months later I wonder, what CPUs are more secure at ...
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Privacy implications of Intel CPU backdoors [closed]

I didn't follow all the episodes about backdoors in Intel CPUs What can intelligence or law enforcement agencies potentially do on a computer equipped with a vulnerable Intel CPU (connected to the ...
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Can speculative execution on intel cpu be disabled?

In the light of all the recent Intel Vulnerabilities with speculative execution, can speculative execution be fully disabled to protect from all this vulnerabilities, from BIOS or OS kernel? Maybe ...
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How to fix Spectre variant 3a and variant 4?e

How I can fix CVE-2018-3640 [rogue system register read] aka 'Variant 3a' and CVE-2018-3639 [speculative store bypass] aka 'Variant 4'? My status for them is VULNERABLE. I have Intel CPU and using ...
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Do Meltdown and Spectre affect other Intel products such as SSDs?

I've found a good deal on an Intel SSD but I don't want to worry about the security hole or the loss of performance from patching it.
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Extracting passwords from recycled machine using Spectre and Meltdown

With Spectre and Meltdown, hackers can extract your password from the CPU cache. If I give someone my computer without the hard drive, can he extract my passwords through the CPU?
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Nessus ADV180002: Microsoft SQL Server January 2018 Security Update (Meltdown) (Spectre)

I have a MS Server 2012 r2 running ArcServe 17.5, which uses MSSQL Server Express 2014. When Nessus runs a scan of this system, I am getting the plugin 105613 - ADV180002: Microsoft SQL Server January ...
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Should I wait until Spectre and Meltdown is fixed in hardware? [duplicate]

I have a Laptop that needs replacing due to age. I will be using this laptop for desktop use, including Office Apps, Development, Running VMs & Web Browsing. I will be using separation using ...
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Meltdown and Spectre regarding Firewalls and Sandboxing [duplicate]

I don't deeply understand Meltdown and Spectre -- all I know is that they are basically keylogging-like vulnerabilities within the CPU, which bypass any application layer stuff; correct me if I'm ...
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What is the significance of Spectre and Meltdown?

Reading up on Spectre and Meltdown attacks again, I don't get why they were hyped so much. These are cache attacks that take advantage of the instruction pipeline processing implementation in ...
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How bits/bytes are handled after performing Meltdown? [closed]

I understand how it works but for example after reading 4 bytes, how do it undertand if it was originally an integer or 4 different characters? Both of them could give a meaningfull result.
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Are new Intel CPUs vulnerable to Meltdown/Spectre?

Has Intel released any information about new processors? According to their advisory a number of processors are susceptible, but it says nothing about when new processors will be fixed. Also Meltdown ...
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how did the meltdown attack break KASLR in 128 steps for a target machine with 8GB RAM with 40bit randomization on a 64bit machine?

In the meltdown official paper released the authors broke the KASLR with 128 steps at worse. Unable to understand how did they come down to that number Paper for reference
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What to do against Spectre-1, Sprectre-2 and Meltdown on Linux and Windows in 01/2018? [duplicate]

How to handle Spectre-1, Spectre-2 and Meltdown for now, in 01/2018? It can almost never be wrong to do the following Stay up to date with your browser and OS e.g. Linux kernel update Update anti-...
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Adobe Flash and Meltdown / Spectre

Many browsers have received updates to protect against the Meltdown and Spectre attacks. I presume these patches relate (solely) to JavaScript execution within the browser. Java in the browser is as ...
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Spectre/Meltdown - Does memory deallocation erase the actual RAM contents?

The other day I've been thinking about Spectre and Meltdown and the ability of one process to access the memory of another. On my Linux system currently I have all JavaScript disabled to eliminate ...
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Meltdown - Reading processes info from leaked memory [closed]

Found this video: https://www.youtube.com/watch?v=De4rBaAdKNA In the video Meltdown is used to read process memory based by PID/name. How it is done? The program looks for task_struct in leaked ...
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Spectre, Meltdown to read SSH keys

I've got a VPS running on Ubuntu, accessed through SSH, passwordless and with a public key. Can Spectre and Meltdown be used to compromise it in order to get access remotely eg by reading the private ...
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How can CPU designers prevent information leaks from speculated execution?

We know about short-term measures to mitigate the Meltdown and Spectre vulnerabilities in certain microprocessors where speculative execution has measurable effects on cache timings (mainly patches to ...
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355 views

Is microcode physically able to mitigate Meltdown?

I am aware that there is no microcode fix for Meltdown available (it has already been answered in various questions), and that the only extant microcode patches (IBRS and IPBP) only help with one of ...
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how do CPU cache side-channel attack fit into the background of Meltdown vulnerability? [duplicate]

NOTE:I know there are similar questions out there, namely this one, but that answer is just an extraction from original paper, which didn't clarify the attack. Additionally I can see from answers ...
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Is it true that meltdown and spectre were intended as debug tools?

I heard from a guy that's involved in low-level (assembler, C for drivers and OSes) programming, that meltdown and spectre weren't actually vulnerabilities discovered only so recently, but they were ...
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On Windows boxes, is patching for Spectre and Meltdown necessary?

From what I've read, Spectre and Meltdown each require rogue code to be running on a Windows box in order for attacks to take place. The thing is, once a box has rogue code running, it's already ...
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Spectre: Problem with Understanding POC - Reading data from cache

I understand the vulnerability (Spectre) and, in theory, what the PoC does. But I do not understand the part of the PoC, when it reads or identifys the data from the cache, between the lines 86 - 108. ...
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Is anyone seeing a performance decrease after applying recent kernel patch fixing Meltdown and Spectre? [closed]

Our company has a lot of CPU intensive operations on our servers, so the performance decrease is a concern for the organization. We did the benchmarks, and it seems that performance is almost not ...
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Meltdown & UEFI

I've been trying to understand the risk of an unprotected BIOS being the victim of an UEFI attack using Meltdown and what the risks are compared to the bug being unpatched in the OS. What is required ...
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Meltdown - PoC - Reading physical address with KASLR disabled does not work

Working with this PoC https://github.com/IAIK/meltdown Running it: # ./secret [+] Secret: Sample text [+] Virtual address of secret: 0x4af528 [+] Physical address of secret: 0x172bc3528 [+] Exit ...
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How does the side channel actually access the contents of kernel memory in Meltdown?

In the Meltdown paper it mentions it can identify kernel memory address being accessed. The part I don't understand is how the FLUSH+RELOAD channel works to identify what the contents of the memory ...
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Are PCs really vulnerable to Spectre type attacks due to virtual user space addressing? [duplicate]

Are Windows OS user programs vulnerable to Spectre and the other recent Intel flaws? Wouldn't the virtual memory assignment in Windows prevent such attacks, or their usefulness? Sorry if I miss ...
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Will patching a higher layer protect against the spectre/meltdown vulnerability in a lower layer?

The question I am about to ask is similar to the following question: Do I need to patch Linux for Meltdown/Spectre if the hypervisor has been patched, and I trust the guest? However, I would like to ...
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Was Meltdown/Spectre discovered in 1991 or 1995?

Wikipedia mentions this paper without going into details: The Intel 80x86 Processor Architecture: Pitfalls for Secure Systems: As mentioned in the preceding scenario, caches present potential for ...
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Are mitigations for Spectre and Meltdown needed in the VMs for dynamic languages other than JavaScript?

Mitigations for Spectre and Meltdown are being added to the JavaScript VMs in Chrome, Firefox, IE/Edge and WebKit. Are similar mitigations also needed in the VMs for other dynamic languages? For ...
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Intel firmware/microcode updates that make processors “immune” to both Spectre and Meltdown?

Recently Intel has claimed the following in a press release (emphasis added): SANTA CLARA, Calif., Jan. 4, 2018 — Intel has developed and is rapidly issuing updates for all types of Intel-based ...
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Why were Meltdown and Spectre disclosed at the same time?

Both the Meltdown and Spectre vulnerabilities were publicly disclosed on January 3, 2018. (6 days ahead of the originally planned January 9). Since their public reveal, there has been some confusion ...
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Meltdown - Reading Process Memory Data

Tried this PoC: https://github.com/mniip/spectre-meltdown-poc Which works for the sys_call_table. I was able to read the syscall sys_read address. Wanted to test it with a sample program to read ...
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Why and where was Meltdown made public before schedule for the first time?

Originally, Meltdown and Spectre had a coordinated disclosure date of January 9, 2018. Some vendors were preparing to release fixes at that time, and were caught by surprise when the vulnaribilities ...
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What is the expected performance impact/loss of meltdown/spectre patches? [duplicate]

The patches related to the mitigation of meltdown and spectre attacks, have they caused significant and noticeable slow down of execution in systems they have been applied to?
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Mitigating Meltdown by checking the faulting address in every page fault?

Short question Would checking if the faulting address for every page fault points to kernel memory reliably detect an attempted Meltdown exploit, on systems that lack Intel TSX (and thus cannot ...
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Reducing resolution of timers as mitigation against Meltdown and Spectre

I have read that Firefox' current mitigation against Meltdown and Spectre (from 57.x) consists of the following: The resolution of performance.now() will be reduced to 20µs. The ...
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Meltdown and Spectre vs. dcache timing and dcache leak issues

I've heard an expert (or "expert") laugh the current focus on Meltdown and Spectre off by arguing that dcache timing and dcache leak issues have been known and around for years (so nothing new there .....
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How can a userspace linux process refer to a kernel address?

I would like help understanding a particular aspect of meltdown. My understanding is that the meltdown bug can be used for a userspace linux process to access kernel memory (indirectly, through a ...