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Teknold
12-10-2016, 03:55 PM
Hello!

I have a likely stupid sounding question, but coming from Windows background, I believe danger from everything.

I'm usually very paranoid, but was tired at one point, real life stress making me crack, I did something stupid - I downloaded some video files that were hosted in https://openload.co/f/

I pretty much regretted my lack of carefulness few days later and deleted them. Issue being, I also had moved them to external hard drive and deleted them from there as well.

But now I'm struggling with paranoia and regret of that one time letting my impulses get out of control.

So my questions are as follow:

1) Is there Mac malware that hides itself inside .mp4 files? Like the file is video file that was expected and it plays, but could something malicious sneak in with it and run in the background without user noticing it? Can Mac malware hide itself inside of mp4 or even image files?

Are there Mac malware/adware/trojans, that can mask themselves with for example .mp4 file extension and when user clicks, it already runs and/or installs something?

For example catvideo.mp4 is instead installer to malware/trojan? Wouldn't there be some window asking about installing or can it just run/install without asking user's allowance?


Or is there a possibility user downloads a video.mp4, clicks on it, video plays normally, but in background something malicious, without user noticing, activates when video was activated?

2) Mac lacks malware that can infect other files, yes? So when I put them on external hard drive, then deleted them, even if there was something malicious, other files there would not have been infected? And using uploading to Mac from that external hard drive would not be a threat?

3) Does Mac malware actually have to ask user to let it run or can it simply sneak in and start running right away?

harryb2448
12-10-2016, 06:02 PM
G'day and welcome to the for ums.

I can see you are paranoid about this virus thing coming from Windows. Yes viruses can infect .mp4 files if you downloaded or used them on a PC without AV software protection. However they cannot execute on a Mac, as no virus can operate on OS X thanks to its Unix basis background. For adware etcdownload Malwarebyts for Mac, see link, and run that in scan mode from time to time. NI trust you are notn using so called Mac Antivirus software? They are a real resource hog and can slow down your Mac whilst they look for Windows viruses which cannot execute. New virus definitions are again Windows virus definitions which etc etc.

https://www.malwarebytes.com/mac/

And have a read of nthis:-


http://superuser.com/questions/445366/can-avi-files-contain-a-virus

Teknold
12-10-2016, 08:30 PM
G'day and welcome to the for ums.

I can see you are paranoid about this virus thing coming from Windows. Yes viruses can infect .mp4 files if you downloaded or used them on a PC without AV software protection. However they cannot execute on a Mac, as no virus can operate on OS X thanks to its Unix basis background. For adware etcdownload Malwarebyts for Mac, see link, and run that in scan mode from time to time. NI trust you are notn using so called Mac Antivirus software? They are a real resource hog and can slow down your Mac whilst they look for Windows viruses which cannot execute. New virus definitions are again Windows virus definitions which etc etc.

https://www.malwarebytes.com/mac/

And have a read of nthis:-


http://superuser.com/questions/445366/can-avi-files-contain-a-virus

Hello and thank your for your reply!

No, I have heard that Mac AVs ruin systems so I don't use them. And that there really are no viruses. I was afraid if .mp4 files could contain Mac malware/adware/trojans, but those can't then hide inside video files and execute themselves while video plays?

I read the superuser article and hoo boy, not sure if I'm lucky or not that I did not know about this while being Windows user... But in mac, they can't execute themselves without asking user to actually let them install themselves?

KevinJS
12-10-2016, 11:06 PM
Use VLC for playing media files, and turn off the option (Preferences/Interface) "Allow Metadata Network Access"

Teknold
12-11-2016, 07:10 AM
Use VLC for playing media files, and turn off the option (Preferences/Interface) "Allow Metadata Network Access"

Thank you for that advice! I am already using VLC, but didn't know about Metada option. That will stop sites from accessing VLC's content?

KevinJS
12-11-2016, 01:02 PM
It will stop any media file that's capable of "phoning home" from doing so.

Teknold
12-12-2016, 08:44 AM
It will stop any media file that's capable of "phoning home" from doing so.

So when media file has ability to call out from your Mac to whoever coded that file, this stops it from doing it? Thank you very much!

KevinJS
12-12-2016, 02:45 PM
So when media file has ability to call out from your Mac to whoever coded that file, this stops it from doing it? Thank you very much!

That's pretty well it. The only media file I'm aware of that has the built-in capability is .mov, the native filetype for QuickTime video. Although it normally plays as a video, it can open URLs in your browser, which should be prevented by limiting VLCs capability. You should ensure that when you open such a file, you use "Open with..." and select VLC, otherwise the file will automatically open QuickTime to play it. You could also direct your computer to use VLC as the default player. I don't bother because I prefer to use QT to play videos recorded on my iPhone. One reason for that is that QT will automatically play the video in the correct orientation, even if it was recorded upside down. iPhone cameras need the home button either to the right in landscape or down in portrait. VLC will not make the correction.

I use most media filetypes and I've never seen any other file attempting to phone home, but given the vast amount of information that can be contained in metadata, I'm not going to say it can't happen.

Teknold
12-13-2016, 09:58 AM
That's pretty well it. The only media file I'm aware of that has the built-in capability is .mov, the native filetype for QuickTime video. Although it normally plays as a video, it can open URLs in your browser, which should be prevented by limiting VLCs capability. You should ensure that when you open such a file, you use "Open with..." and select VLC, otherwise the file will automatically open QuickTime to play it. You could also direct your computer to use VLC as the default player. I don't bother because I prefer to use QT to play videos recorded on my iPhone. One reason for that is that QT will automatically play the video in the correct orientation, even if it was recorded upside down. iPhone cameras need the home button either to the right in landscape or down in portrait. VLC will not make the correction.

I use most media filetypes and I've never seen any other file attempting to phone home, but given the vast amount of information that can be contained in metadata, I'm not going to say it can't happen.

Thank you for your answer!
So mp4's don't have built-in capability to phone home, but there might be slight chance someone can pull it off?

KevinJS
12-13-2016, 10:11 AM
They may. I don't know. Best to play safe and treat them as though they can.