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Questions tagged [cpu]

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1answer
19 views

Is it possible to completely prevent Speculative Execution Side-Channel attacks?

I'm learning about computer architecture recently, and I heard that branch prediction is really tricky but may improve the efficiency of cpu a lot, then I came across this term. My question is that is ...
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0answers
37 views

If you buy a used hard drive or CPU, how to guarantee it doesn't have anything installed or running on it [duplicate]

Say you buy a used hard drive, or a computer (wondering about both cases, something that is just a drive for storage, and something that is an actual running chip). I am not interested in whether or ...
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2answers
46 views

Effects of new random Session token for each HTTP Request

On successful authentcation, a web application issues a session cookie that is a constant length string of apparently random hex characters. ...
0
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1answer
43 views

Data Execution Prevention X vs NX

My lecturer posted this in his slides and I have no idea what he is trying to say. I quote from his slide: Windows DEP = Data Execution Prevention Old “X” idea: must allow explicitly, current ...
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1answer
54 views

Security implications of running multiple virtual machines on shared CPU cores

Recently there has been the recommendation to disable hyperthreading. I was wondering if there is an increased risk of an attack or information disclosure when multiple virtual machines use the same ...
13
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1answer
4k views

New CVE-2018-5407 “PortSmash vulnerablity” in Intel CPU

I just heard in the news: Intel CPUs impacted by new PortSmash side-channel vulnerability. Is it as threatening as Meltdown/Spectre? Is it patched? What should we do to be safe? Does it affect AMD CPU'...
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0answers
62 views

Will More vCPU's and RAM Help Protect Against Some Smaller Scale DDoS Attacks?

Obviously having more vCPU's (virtual CPU's) and more RAM by them self won't be able to alone help stop and/or prevent a DDoS attack, but let's say after a DDoS attack is finished and/or slowing down ...
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8answers
24k views

If I know the CPU architecture of a target, can I send instructions embedded in an image?

Can I send instructions embedded in an image to a target, if I know his CPU architecture?
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1answer
34 views

Do any speculative executation attacks affect ARMv7 CPUs?

Do we know if there are speculative execution attacks that affect ARMv7 CPUs at this time? Are there any theoretical risks that need further investigation?
12
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2answers
498 views

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 ...
3
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1answer
192 views

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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2answers
143 views

How protected mode in CPU is really implemented?

I know what is real and protected mode of cpu execution. But how CPU implements protected mode ? AFAIK cpu does everything what the program says it to do. Where is the protected mode behaviour ...
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2answers
155 views

Why are Protection Rings called rings?

Protection rings are different privilege levels granted to software, with the kernel being the most privileged, applications the least privileged, and drivers somewhere in between. My question is why ...
3
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1answer
171 views

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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2answers
184 views

What can give physical access to CPU?

If an attacker has an unlimited physical access to CPU, but does not have access to memory, including RAM, can he attack and gain access to the user's data? I heard the opinion that this is ...
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2answers
87 views

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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0answers
280 views

CPU Usage at 100% due to explorer.exe with malicious threads.

(Keep in mind I'm not a computer expert so I'm trying my best here.) Hello, recently I've had a problem with my computer causing my CPU Usage to go to 100%. This makes me unable to move/create/rename ...
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1answer
73 views

Does Speculative Store Bypass Attack Require Assembly/Source Code Knowledge?

ok, so the gist of speculative store bypass attack to my understanding is that, cpu chooses the most frequent code path, bypass the if/else test and just assumes that it's true/false and then execute ...
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1answer
127 views

Do Spectre(-NG) and Meltdown affect Mill?

Given what is publicly known about the Mill CPU, would it be affected by Spectre(-NG) or Meltdown style attacks? Why/why not?
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0answers
168 views

What Spectre V2 patches fixes which vulnerabilties on Linux?

Let's assume I have a computer with a pre-Skylake Intel processor that doesn't have microcode mitigating the Spectre V2 attack. Then to my understanding, if the kernel and all user-space applications ...
7
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3answers
217 views

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 ...
8
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1answer
932 views

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 ...
7
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2answers
587 views

Capability of microcode hacking?

Before Spectre and Meltdown, I've never heard of users updating microcode on a chip through firmware or otherwise. I actually thought it was written into the silicon and immutable. Now I'm seeing a ...
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0answers
85 views

Why is spectre and meltdown affecting all cpu architectures? [duplicate]

My question is regarding the recent issue of meltdown and spectre that has affected "all" processors. Initially I though it was just x86_64 architecture based processors. So when they said it affects ...
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2answers
501 views

Does recent Intel hardware mitigate Meltdown at the hardware level?

Recently a security researcher made the following claim via Twitter (emphasis added): If you're running Windows, I'm about to publish a tool that checks if you have the "Variant 3: rogue data cache ...
5
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2answers
950 views

Are VIA CPUs vulnerable to Spectre/Meltdown attacks?

I couldn't find any information about the recently published Spectre/Meltdown attacks affecting VIA CPUs. Are they also affected by this vulnerabilities?
5
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1answer
449 views

What was state of the art knowledge on security of speculative evaluation when it was introduced to Intel CPUs?

Many sources claim that almost all Intel x86 CPUs back to Pentium Pro are vulnerable to the Meltdown attack. Pentium Pro was introduced to the market in 1995. What was the state of the art knowledge ...
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3answers
725 views

Do the Spectre and Meltdown CPU bugs affect AMD in addition to Intel?

If a server or or PC is running AMD CPUs, will those be affected by the Spectre and/or Meltdown bugs currently effecting Intel chips? Why or why not? What makes it affect one and not the other? How ...
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2answers
464 views

How does the Intel CPU design flaw affect us? [closed]

Today, I saw this in the news. I'm hesitant to install the fix, because I've heard it would slow down IO 50%, which is not acceptable for me. But a guy said that the flaw allows JavaScript in the ...
4
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1answer
369 views

Does the main OS run “virtualised” under the ring -1 hypervisor?

After reading this answer which explains that modern CPUs have a ring -1 that is running a hypervisor on the CPU and handles vmenter & stuff, I am wondering: The main operating system, like the ...
5
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3answers
479 views

Understanding the scope of Intel hyperthreading errata KBL095

Recently, many motherboards supporting skylake or kabylake, got a uefi update described as cpu microcode security update for a specific Intel errata, described by Intel as : Short Loops Which Use ...
2
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1answer
692 views

Intel Management Engine vulnerabilities in CPUs without vPro

Intel Management Engine (ME) imposes a security risk (see here for example). As I understand ME is a part of Intel vPro. Does having an Intel CPU without vPro support mean ME is not fully functional ...
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0answers
250 views

Frequent heavy CPU load from firefox browser -> malware? [closed]

Since recently I started to get very heavy CPU load on my 64bit Debian 9.0 Cinnamon machine. I have all my packages up to date including Firefox-ESR. Often the load is so heavy that I can hear my CPU. ...
0
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3answers
326 views

Can OS protect us from backdoored CPU? [closed]

I was wondering if O.S. can act in such a way to hide from CPU what it is doing? I know that everything is computed only in CPU, but O.S. decides what that is, and keeps track of file system, etc. For ...