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164 votes

Is it true that meltdown and spectre were intended as debug tools?

It's not even remotely true. Although you can use a Meltdown or Spectre attack to inspect the internals of a program in the way a debugger can, a proper debugger is much faster, easier, and more ...
Mark's user avatar
  • 34.6k
121 votes

Meltdown and Spectre Attacks

This answer is an attempt at addressing simply the main concerns. The details here might not be exemplary accurate, or complete. I'll try to link to more detailed explanations when possible. What is ...
M'vy's user avatar
  • 13k
85 votes

On Windows boxes, is patching for Spectre and Meltdown necessary?

the only point of easy penetration to a system seems to be via javascript running in a web browser. How about Flash? Java? Silverlight? VBA in an office document? Any applications that load web-pages ...
Hector's user avatar
  • 11k
79 votes
Accepted

Is it true that meltdown and spectre were intended as debug tools?

A normal debugger uses documented API/syscall/instruction to look at state of a process it is permitted to access. Just being a debugger alone cannot bypass OS memory protection, otherwise anyone who ...
billc.cn's user avatar
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45 votes
Accepted

Spectre/meltdown on a GPU

First of all you would not normally expect kernel memory to be mapped in a GPU. Even if you did modern GPU's generally don't have much in the way of support for sharing memory between processes. ...
Hector's user avatar
  • 11k
33 votes
Accepted

Are new Intel CPUs vulnerable to Meltdown/Spectre?

The processors that were already announced and are about to be launched in the near future will still be vulnerable to both Spectre v2 and Meltdown if patches and/or firmware is not applied correctly. ...
Tom K.'s user avatar
  • 7,975
31 votes

On Windows boxes, is patching for Spectre and Meltdown necessary?

In my world, applying patches is a given. We're going to do it and it takes an exception to NOT apply a patch. Right now, those are exploits we know about for Spectre and Meltdown. However, what's ...
baldPrussian's user avatar
  • 2,778
22 votes

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 ...
Nat's user avatar
  • 1,441
20 votes
Accepted

How can SharedArrayBuffer be used for timing attacks?

SharedArrayBuffer allows two threads to share state, so one can operate as a "clock" (incrementing the timing signal) and the other can read the "clock". Additionally, the availability of the Atomics ...
David's user avatar
  • 16.1k
19 votes

Just how bad is Spectre?

The core of the Spectre attack is to use mis-training of the CPU's branch predictor to cause the CPU to speculatively branch to an attacker-selected fragment of code while executing the target program,...
Mark's user avatar
  • 34.6k
18 votes

Spectre/meltdown on a GPU

A GPU (Graphical Processing Unit) is not vulnerable to spectre/meltdown attacks. This is due to various reasons: A GPU is a completely differently designed processor. It does not run privileged ...
LvB's user avatar
  • 8,943
17 votes

Spectre/meltdown on a GPU

Nvidia has released updates today (Jan 9 2018) dealing with the issues. So I would assume there are risks since they have created updates. http://us.download.nvidia.com/Windows/390.65/390.65-win10-...
Viktor Mellgren's user avatar
16 votes

Should Virtual Machines be patched for Meltdown and Spectre?

My understanding, first off, is that the OS / hypervisor patch only mitigates Meltdown, not Spectre. Second, you patch the hypervisor to prevent a VM from reading memory belonging to the kernel of ...
Mike Ounsworth's user avatar
13 votes
Accepted

Are Meltdown and Spectre only exploitable with compiled code?

No, interpreted or JIT'd code is also vulnerable According to multiple sources, the attack can be exploited via JavaScript in browsers. An excerpt from the Windows Blogs on Microsoft: Today, ...
rink.attendant.6's user avatar
12 votes
Accepted

Is anyone seeing a performance decrease after applying recent kernel patch fixing Meltdown and Spectre?

The performance impact will vary greatly depending on what the program does. After the Meltdown patch (KPTI) whenever there is a context switch from user-space to kernel-space there is a significant ...
Tux's user avatar
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11 votes
Accepted

Why were Meltdown and Spectre disclosed at the same time?

*Update: This article seems to cover everything. The attack papers share many of the same authors and use similar but previously unknown attack vectors. Both exploits resulted from the same (or at ...
Hector's user avatar
  • 11k
11 votes
Accepted

Was Meltdown/Spectre discovered in 1991 or 1995?

The Wray paper is about categorisation of covert channels, and from a rapid reading, it does reference an attack on a cache by two processes explicitly loading memory locations, but to be used as a ...
M'vy's user avatar
  • 13k
10 votes
Accepted

Are new AMD processors more secure than Intel ones?

They are both about equally terrible and still highly vulnerable to Spectre. Unfortunately, you would have to have access to confidential design documents in order to even begin answering this ...
forest's user avatar
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9 votes
Accepted

What does Spectre mean for public cloud computing?

Spectre is far harder to use than Meltdown. In a cloud hosting situation, an attacker needs to know: What software the target is using Where in memory that software is Where in memory the target ...
Mark's user avatar
  • 34.6k
9 votes
Accepted

How does Meltdown/Spectre impact Intel SGX?

Spectre. Intel SGX enclaves are indeed vulnerable to the Spectre attack as recently shown by researchers [1]. Their sample code manages to read a secret from protected SGX memory. Update Mar 7th, ...
Florian's user avatar
  • 248
8 votes

On Windows boxes, is patching for Spectre and Meltdown necessary?

Yes, because it can be used for privilege escalation. Usually, if an attack compromises a host, they only have user privileges. Using this vulnerability, they can escalate privileges by leaking ...
Daniel Grover's user avatar
8 votes

On Windows boxes, is patching for Spectre and Meltdown necessary?

Install the patches unless you have a very strong reason not to. The approach you describe can basically be summed up as this: I know about exploit X. I could patch my OS to resolve exploit X, or ...
Cort Ammon's user avatar
  • 9,256
7 votes

Meltdown and Spectre Attacks

Simple tips In addition to M'vy's excellent answer, I just want answer this question: What can I do in order to be safe? Spectre, Meltdown and Rowhammer are CPU conceptual bugs, so they couldn't be ...
F. Hauri  - Give Up GitHub's user avatar
7 votes
Accepted

Is branch predictor flush instruction a complete Spectre fix?

A predictor-flush instruction is necessary but not sufficient for protection from Spectre. A full protection against the Spectre attack requires two things: Flushing the branch predictor state on ...
Mark's user avatar
  • 34.6k
7 votes
Accepted

What is the relationship between the GPZ research titles and Meltdown and Spectre?

If I understand you correctly you ask how the three issues shown by GZP map to the names Meltdown and Spectre. You'll find the answer at the beginning of this post from Google Zero Project: So far, ...
Steffen Ullrich's user avatar
7 votes
Accepted

How are exploits like Meltdown and Spectre noticed?

I think you might be confusing the terms exploit and vulnerability. A vulnerability is a "hole" in the security, caused by a bug or poor implementation. They are detected by security researchers (...
Jakub's user avatar
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7 votes
Accepted

Are Meltdown and Spectre exploitable on 32-bit Linux platforms?

Any CPU that performs speculative execution is vulnerable to Spectre, so yes, 32-bit OSs are vulnerable. Meltdown is an issue with how Intel CPUs enforce memory protection while performing ...
Mark's user avatar
  • 34.6k
7 votes

Are MCUs (Like arduinos) effected by Meltdown?

In general, no, for several reasons. First, Meltdown is an issue with how Intel chose to handle invalid memory accesses during speculative execution. A couple of ARM designs are vulnerable to a ...
Mark's user avatar
  • 34.6k
7 votes
Accepted

Could Meltdown/Spectre be exploited from C#/.Net (or other managed languages or the Midori OS)?

Could Meltdown be exploited from C#/.Net (or other managed languages)? It can even be done from JavaScript.
Hector's user avatar
  • 11k
7 votes
Accepted

Why and where was Meltdown made public before schedule for the first time?

I followed the news of these attacks with a lot of interest starting on Jan 3rd, and have done some digging back to see what else people had been saying prior to disclosure. The embargo was ...
David's user avatar
  • 1,416

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