I am a developer & ASO specialist. As you guess, I have different customers. I am downloading 5-10 files per day from my customers. I learned that it is possible to hack MacOS via mp4, apk files, txt files, images, etc. but my customers always send their apks, app images, txt files, app videos(mp4), etc. Only 10-15 percentage of customers are my previous & reliable customers. Remains are new customers and I have no idea their files are safe or not, they may want to hack my computer or log my works to steal my approach, etc. Finally, How do I know if a file is 100% reliable, before opening it? Is there any solution for this problem? (any secure mac app, etc.) I'm using virustotal but I have no idea that I am safe or not. Thanks...

  • safest method, use another Mac, to download, the scan for virus before transferring to you mac
    – Ruskes
    Sep 21, 2022 at 18:55
  • What do you think for APK files? I have also Android smartphone, sometimes I am getting APK files, is it risky? Is it possible to be hacked with APK, with APK hack do attackers hack my macbook(by hacking network)? Sep 21, 2022 at 19:04
  • I do not know, I am not a hacker
    – Ruskes
    Sep 21, 2022 at 22:16

1 Answer 1


Saying that "it's possible to hack macOS via mp4" is oversimplifying what happens.

It's extremely rare that the file is actually an mp4 - what's more common is it's a program disguised as an mp4, and the user clicks through the warnings when they try to open it. Alternatively, people are told to download a program to view the "mp4" but the mp4 is completely fake and has no contents.

When you receive a file from an untrusted source, you can do a few things to verify that it is not an executable program file:

  1. Ensure that Finder > Settings (Preferences) > Advanced > Show all filename extensions is enabled. This will ensure that you don't receive a file named abc.mp4.app and miss the .app extension.
  2. If you receive an alert when opening a file that you expect to just contain media, read it carefully. If it seems like the alert is warning you that you might be running something, cancel and re-examine the file.
  3. If you are dealing with data that is likely to be malicious (which is very different), you should set up a virtual machine and open the files in this virtual machine.

On macOS, most executable / "runnable" files are .app application bundles. These can be run by double-clicking them. However, also be aware of things like .command or even files with no extension. These files will still be marked as executable and will be quarantined (meaning you will see an alert before opening them the first time).

Examples of files that are executable/"runnable". For each of these, the type is described as an "application," "script," or "executable".

Files that will run a program when opened

Furthermore, if you download files like these and open them, you'll see an alert like this the first time you run it:

X is an app downloaded from the internet. Are you sure you want to open it?

  • Very good answer. So if a file is not .app, does it guarantee that it is safe and it does not contains any keylogger or other hacking things? For example is it possible to be hacked by "abc.mp4" file? Sep 21, 2022 at 19:01
  • 1
    I amended it slightly to show multiple examples of things that could run code when opened (and an example of the alert you'll see when opening them for the first time.
    – Ezekiel
    Sep 21, 2022 at 19:21
  • 1
    See how in the Get Info alerts the "Kind" field makes it clear this will run some sort of program or script
    – Ezekiel
    Sep 21, 2022 at 19:22

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