Question Is it possible for windows defender to not detect a virus?

[moooshrooms]

I don't have the money to pay for antivirus so I just use windows defender, I recently noticed that my mouse moved by itself so I freaked out and did a complete scan but it came back clean so I assumed it was just because the website was loading extremely slow and my mouse lagged. That was a couple of days ago and I haven't noticed anything else but just now a random tab opened, it was completely black with a white title bar and closed a second later which has never happened before. I've scanned multiple times with microsoft defender and norton power eraser (which I know norton isn't the best but power eraser is free lol) and it all came back clean.

Should I be worried anyways? Is there something else I should scan for just in case that microsoft defender doesn't scan for?

 

[Wolfshadw]

I'd probably go ahead and scan with Malwarebytes (free) to check for possible malware.
No anti-virus software is 100% secure. No anti-virus software is going to find every possible virus out there. The best you can do is stay away from questionable sites, scan with multiple tools if you feel your system has been compromised, and have a back up of your data in the event that your system needs a format/reinstall.

-Wolf sends

 

[Ralston18]

Windows Defender/Security does a very good job overall.

Malwarebytes (free) can be used as a backup of sorts as long as you do not leave it running continuously in the background. Just run as necessary for backup AV scanning.

What Windows version are you running?

Any recent updates of any sort? New installs?

Could have simple been some glitch - corrupted software perhaps.

Start by manually downloading, reinstalling, and re-configuring the mouse drivers.

 

[moooshrooms]

I'd probably go ahead and scan with Malwarebytes (free) to check for possible malware.
No anti-virus software is 100% secure. No anti-virus software is going to find every possible virus out there. The best you can do is stay away from questionable sites, scan with multiple tools if you feel your system has been compromised, and have a back up of your data in the event that your system needs a format/reinstall.

-Wolf sends

I ran Malwarebytes and it came back clean, so I'm pretty much in the clear then?

 

[moooshrooms]

Windows Defender/Security does a very good job overall.

Malwarebytes (free) can be used as a backup of sorts as long as you do not leave it running continuously in the background. Just run as necessary for backup AV scanning.

What Windows version are you running?

Any recent updates of any sort? New installs?

Could have simple been some glitch - corrupted software perhaps.

Start by manually downloading, reinstalling, and re-configuring the mouse drivers.

I ran a Malwarebytes scan and it came back clean. I'm running windows 10 and I'm not really sure what you mean by new installs but as far as I'm aware nothing has been downloaded/installed that wasn't from me and nothing suspicious pops up in task manager. I'm also not sure how to manage the mouse drivers, however, I will say that it still moves on its own but it's really only about an inch or two up/down/left/right from where I moved it which I probably should've explained in the og post. It happens with my built-in mouse and my usb mouse. I'm not sure if it's important but my built-in mouse is also sunken down in one corner but I highly doubt that's the cause. Either way, as long as it's not a virus then I'm not too worried about fixing it since like I said it really only moves a small amount. I just wanted to make sure it isn't happening because of a virus.

 

[Wolfshadw]

I ran Malwarebytes and it came back clean, so I'm pretty much in the clear then?

Probably. Again, no anti-virus software is ever 100% accurate. If it were my system and Windows Defender, another Anti-virus software program, and Malwarebytes all came back clean, then I would assume that my system was clean and secure.

-Wolf sends

 

[Ralston18]

Whichever mouse you are using, disable the other mouse.

Determine if the ghost movements stop.

Also: "my usb mouse. I'm not sure if it's important but my built-in mouse is also sunken down in one corner."

As in physically damaged?

 

[moooshrooms]

Also: "my usb mouse. I'm not sure if it's important but my built-in mouse is also sunken down in one corner."

As in physically damaged?

Depends on what you consider physically damaged, I have an HP Pavilion gaming laptop so the built-in mouse is just one big touchpad with no separated left/right buttons, it's sunken down just below the rim in the left corner if that makes sense. It still works normally though so I'm gonna assume it's fine with no actual damage. At most, it sometimes reacts like I'm clicking when I'm not but that's about it.

As for disabling the other mouse, the movements seem to have stopped for now.

 

[SkyNetRising]

As for disabling the other mouse, the movements seem to have stopped for now.

Probably there is some dust or hair in optical sensor of the mouse. Clean it.