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Firefox engineers discover a Windows Defender bug that causes high CPU usage

bugzilla.mozilla.org

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Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#161

Post by joveian »

Strom wrote: post #101
Narishma wrote: post #96

Earlier quoted context omitted.

I don't think you can disable it anymore in recent versions of Windows unless you install another AV software.

You can disable it. First you have to disable the tamper protection and real time protection in the GUI. Now the real time protection will come back automatically in some time, unless you do the following. If you have a Pro version of Windows there is a group policy setting for it. [1] If you have Home, you can achieve the same effect by manually tweaking the registry. [2] -- [1] Computer Configuration > Administrati…

Thank you, I just disabled it on my fully offline game system. Hopefully a few games that previously crashed will work now :/.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#162

Post by mizzao »

ravenstine wrote: post #46

Windows Defender is a long standing bug in the Windows operating system. ;) My impression is that its invention was for the sole purpose of eradicating the idea that Windows is insecure and prone to viruses, which explains why it can be overzealous and CPU hungry. I would only enable it for family members who don't know what they are doing. For some reason, I haven't needed any form of active virus scanning in someth…

I always disable Defender on my Windows machines as it eats both CPU and disk cycles for no reason, slowing things down to a halt. Was really noticeable on my Surface Book, which was otherwise a great machine.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#164

Post by jquery »

genewitch wrote: post #145
jbritton wrote: post #125

Earlier quoted context omitted.

I had always assumed that one application could not touch the memory of another application. Does running as Admin allow breaking this boundary?

cheatengine, wemod, and so on would not be able to work if this were the case. Thankfully those all work, at least up to windows 10!

They work just fine in windows 11 so far.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#165

Post by jdthedisciple »

tomrod wrote: post #82
fsckboy wrote: post #81

Earlier quoted context omitted.

firefox browser share is teeny tiny these days

Teeny tiny multiplied by 7 Billion by 365 days per year by 24 hours per day by a fraction of a kW does add up.

*8 Billion sir

https://www.worldometers.info/world-population/

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#166

Post by bboygravity »

Yoric wrote: post #85
psychphysic wrote: post #31

Earlier quoted context omitted.

I have malwarebytes premium and defender CPU usage is nearly 100% at times bringin Firefox to a halt. Chrome works fine..I've been blaming Firefox so far.

In my experience (as a former Firefox dev), antivirus / antimalware software are really poorly behaved. They tend to: - require admin rights (which means that if they have vulnerabilities, it can take control of the entire machine, even if Firefox itself is sanboxed); - monkey-patch the Firefox executable in memory, which works (when it does) as long as the version of the software tracks closely the version of Firefo…

This almost reads like Defender makes machines less secure on purpose.

Makes me wonder: Does windows Defender just double as another deliberate NSA backdoor?

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#167

Post by foepys »

bboygravity wrote: post #166
Yoric wrote: post #85

Earlier quoted context omitted.

In my experience (as a former Firefox dev), antivirus / antimalware software are really poorly behaved. They tend to: - require admin rights (which means that if they have vulnerabilities, it can take control of the entire machine, even if Firefox itself is sanboxed); - monkey-patch the Firefox executable in memory, which works (when it does) as long as the version of the software tracks closely the version of Firefo…

This almost reads like Defender makes machines less secure on purpose. Makes me wonder: Does windows Defender just double as another deliberate NSA backdoor?

Why would Microsoft need to put a NSA backdoor specifically into Defender when it could put it anywhere else into Windows with their monthly patch? It doesn't make sense to single out Defender.

The same is valid for Apple, Google, and every other US company.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#168

Post by monocasa »

jchw wrote: post #155
userbinator wrote: post #152

Earlier quoted context omitted.

There are protected processes, and protected processes light, but those are not used by most software (mainly anti-malware afaik.) ...and DRM.

Although that was definitely the intent, I actually don't know about specific things that use it. I'd love to hear what actually uses it. (I don't think Widevine l3 does, for example.)

I seem to recollect that iTunes did, but maybe that was just on OSX.

Re: Firefox engineers discover a Windows Defender bug that causes high CPU usage

#170

Post by ComputerGuru »

AraceliHarker wrote: post #160

I remember some people reporting that their old PCs with unsupported CPUs got a high CPU usage after installing Windows 11, and I remember some people saying that it was because they lacked TPM, which increased the CPU load. But it turned out to be just a bug, didn’t it? After all, features like memory randomization that require TPM couldn’t be enabled on Windows 11 anyway, and similar CPU usage spikes were seen on W…

Memory randomization shouldn’t require a TPM.
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