I would like to protect my flash drives to being infected when I put it in another computers or devices. After some research, I found that I will not be able to reach this level of protection by using only software solutions (correct me if I'm wrong).

However, I don't have a flash drive with hardware protection and my only way to get one is importing (it will not be cheap). I also found that SD card's switches against writing is not in a hardware-level, so I kinda have to trust that a potentially infected computer will respect it, which is not a good idea.

So, my question is: is there a trustful way (using USB) to put my files into another computer without my USB stick (flash drive or SD card) being infected?

  • I used to work-around this problem by using an SD card (which does have a write-protect slider switch) and then using a multi-function card reader (connects to the computer on USB, and has slots for SD cards, MicroSD cards, etc). – user88917 Feb 5 '20 at 6:56

You cannot protect the stick from being "infected", if by "infected" you mean that the other computer writes a malware file onto it - unless you have a USB stick with a hardware write protection.

What you want to protect is your own computer against executing that file from the USB stick and thus becoming infected.

You can achieve that in several ways, depending on how you judge the risk:

  • Throw away the USB stick after the transaction
  • Re-Format the USB stick
  • Do a malware scan of the USB stick

Connecting the (possibly "infected") USB stick back to your computer is rather low-risk: You know for sure that it is a simple USB stick (and not some kind of active USB attacking device). Thus, the only danger would be if your OS automatically executed some file automatically - this is possible, but most modern OSes have protections against that.

If you wipe the stick by formatting it, any possible malware file will be removed.


Yes there is.

You want a forensic USB Write Blocker.

The write blocker plugs into the questionable computer and your USB plugs into the write blocker, allowing only reads from your thumb drive and blocking writes.

Write blockers start at around $150 and go up.


"If you wipe the stick by formatting it, any possible malware file will be removed."

Not necessarily, see other current thread.

"You want a forensic USB Write Blocker."

Yo dawg, I heard u like write blockers. So I put a write blocker in your write blocker so you can prevent the firmware of the write blocker from being overwritten while it's blocking writes to the USB drive. There are write blockers with upgradable firmware (laughs with his Tableau). iirc some have also the option to (write) protect the firmware, otherwise OP would need to do this himself.

OP can also try to write protect the flash directly without relying on firmware by using the WP pin of the chip. With BGA and/or many chips on the USB drive it gets a bit harder of course.

If OP is just copying files from A to B on local computers, he/she/it might want to substitute his/her USB data transfer setup with a diy data diode (probably cheaper than the write blocker^^).

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