Due to security reasons, I need an USB that has the switch to set it physically read only, because in this way I can be 100 % sure that it can't get infected when I connect it to an infected device. I can not find any good and trusted brand that sell USB with that switch in my country, so people suggested me to use and SD card that has that switch. I found some good SD cards with that switch, but sadly I need a SD card reader to connect it to USB ports (something like this https://amzn.eu/d/ewl1uU9).

So I'm wondering: If I turn on the read only switch of the SD card, I put the SD card in the SD card reader and I connect the SD card reader to an infected PC, could a virus still infect the SD card reader firmware? If the answer is yes (I afraid it is), are there any other solutions to connect a USB or something similar to a PC and be physically protected?

Yes, I'm pretty paranoid, but I was used to use DVD to do that stuff, but now with 4 or 8 GB you can't do much, and some PC manufacturers are sadly removing DVD players

  • There are various USB write blockers available
    – paj28
    Commented Apr 20, 2023 at 16:33
  • @paj28 I saw them, but they are so expensive compared to the good old DVD
    – koxige9113
    Commented Apr 20, 2023 at 17:02

1 Answer 1


The Write Protect on the SD card standard is essentially a Honor System. The card reader host must choose to honor it. That's it.


If the malware can get the sdcard reader to ignore this, it will be writable.

There are Write once read many (WORM) USB drives. They are not cheap though.

  • damn, so I can't use an SD Card. I saw the WORM USB, but damn 32 GB are 150 $. I miss DVD so much :(
    – koxige9113
    Commented Apr 20, 2023 at 17:01

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