Does WP(Write Protect) pin of a USB flash memory controller prevent tampering with its firmware?

I want to have an USB stick that I can make it read-only and insert it in any untrusted PC without risking a silent BadUSB infection.

I was thinking about finding an USB stick that has this WP pin in its controller and DIY mod an external switch to it for Write-Protection.

If you have any other simple/cheap solutions to have a 32-/64gb device that can be Write-Protected, please let me know.


No, the Write Protection pin will not protect the USB drive from being written into, and is not there to protect the firmware from being rewritten. That pin advertises to the computer that it prefers not being written into. It's the OS that decides if will honor that request or not. On Linux, you can bypass that and write anyway.

Second, the firmware uses another channel. You don't just plug in the drive and rewrite a file. You need special software to access the firmware, dump it, edit it, and flash it back. Some USB devices need to be plugged in with special pins shorted to enable firmware rewrite. And as there are lots of different USB controllers out there, the solution only works for one controller.

So, don't worry. It's possible to automate that, but it's too difficult, there's a lot of moving parts to care of, and there are easier vectors, like replacing your files with an executable with the same name and icon...

  • Are you sure you are not confusing the WP pin with the SDcard protection switch? – learner May 12 '20 at 6:45
  • 1
    check this: techoverflow.net/2019/10/17/… Do you still think that it is a graceful protection or maybe it really enforces write protection? – learner May 15 '20 at 8:30

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