Someone Copied Files From USB: How to Know?

Here’s how to tell if someone copied files from your USB flash drive to their computer:

It’s possible to check the last time a file was accessed, and the time stamp would tell you when someone copied it.

However, it depends on what file system your USB drive uses: FAT or NTFS. Unortunately, FAT systems don’t track update times. 

So if you want to learn all about how to tell if someone copied files from your USB drive to their computer, then this article is for you. 

Let’s get started!

How to Know if Someone Copied Files From Your USB ?

How to Know if Someone Copied Files From Your USB to Their Computer?

Data safety has been one of the hot topics for a long time.

How safe are your files?

Where should you store them, and who should have access?

Are cloud drives secure?

To avoid all of these issues, many people choose to play it safe and keep their files on a USB stick.

After all, when your files are stored on a physical device, and you know where that device is, the files will be much safer.

But, on the rare occasions when you loan that device to someone or leave it unsupervised, can you see if your important files have been tampered with?

Unfortunately, your options for doing this are likely more limited than you might think.

How Safe Are USB Drives?

USB drives are usually considered safe places to store your data – from a software perspective.

Hand holding white USB drive on white background.

This means that since USB sticks don’t run complex software or get information from a server, they are less likely to be hacked or broken into.

That’s especially the case when they aren’t plugged into your computer. At that point, they’re just pieces of plastic and fiberglass hanging around in your pocket.

However, it might be important to mention that researchers have found that hackers can hide sniffer software in the small chips found in USB sticks.

This software would allow the hackers to control the device remotely without the user ever being aware of it.

But, the most significant security concern with a USB flash drive comes from the very fact that it’s a physical device.

Storing important files on a small device that can easily get lost or stolen is hardly a smart move unless you tie it to your wrist or protect it with a password.

Can You Tell if Someone Copied Your Files?

The short answer to this question is—no. There are no reliable ways to tell whether someone copied files from your USB device.

One technique could maybe help you, but it’s far from certain: you can check when each file on your computer or USB device has been last accessed.

And, to copy a file, you have to access it.

Hypothetically, you can check when a file has been last accessed, and the time stamp would be an indicator of when someone copied it.

Even though this is an unreliable technique, it’s pretty easy if you want to use it.

Simply right-click on the file you want to check, and click on “Properties.” There, you’ll see when the file has been created, modified, and last accessed.

There are two main issues with this approach.

Files Are Accessed Regularly

This is a glaring issue: “accessed” doesn’t really have to mean anyone came close to touching your file.

Your PC doesn’t interpret “accessed” as “opened” or “copied.”

Files are being accessed regularly by different services running on your computer.

For example, anti-malware tools access files to check them for viruses.

So, if you give your USB to someone, get it back, and check the “accessed” timestamp, chances are you’ll see the moment when they inserted the USB device into their PC.

Their computer likely did a quick virus scan or other types of checks that would modify the “accessed” time.

Woman using laptop with USB drive plugged in.

Also, your PC might execute a check when you insert the device.

Even worse, your antivirus doesn’t need to check for the file access times to be updated.

Simply opening the containing folder with File Explorer might cause it to read the files (maybe to get a preview image) and you’ll lose the access time just like that.

Many USB Drives Don’t Update Access Times

USB flash drives use a file system called File Allocation Table (FAT), unlike your computer that uses a different system called New Technology File System (NTFS).

Here’s the problem: FAT systems don’t track update times.

Windows formats all removable storage devices this way, so you most likely won’t get relevant information by checking access times anyway.

How Do You Improve the Safety of Your USB?

How can you ensure that your files aren’t compromised if you do end up losing your USB flash drive?

Here are a few things you can do.

  • Encrypt the data: You can use an encryption tool to protect your data even before you put it on the USB drive. The device trying to interpret it would need to have the same encryption tool installed to read this data.
  • Use an encrypted USB: USB devices use hardware encryption: when inserted into the USB port, they’ll require a password. You create this password the first time you insert the USB into your computer, and the flash drive can’t work without it.
  • Encrypt files on your USB: You can use encryption software to protect specific folders or files on your thumb drive. You can also create hidden partitions for additional security.

Unsafe to Plug Phone Into Work Computer to Charge?

How safe is it to charge your phone at your work computer?

Can your employer access personal information on your phone if you do so?

The short answer is yes, but it’s a little complicated.

Plugging your phone into a computer creates a situation where it is definitely possible for the computer to see personal information on the phone. 

That said, there are security features and protocols that make this hard, meaning it isn’t always likely.

Learn all about what your employer can see when you plug your phone into a work computer with this in-depth article.


  • Theresa McDonough

    Tech entrepreneur and founder of Tech Medic, who has become a prominent advocate for the Right to Repair movement. She has testified before the US Federal Trade Commission and been featured on CBS Sunday Morning, helping influence change within the tech industry.

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