The USB is Write Protected: Why?

USB write protected means the USB cannot be written to. But why?

There are really only two reasons why a USB stick is write protected.

#1 The USB is corrupted in some way and is no longer working properly. It’s actually very easy to destroy a USB stick and the most common way is sending multiple write threads to the device. So for example, you decide to copy a bunch of files form your computer to your USB stick. While that data transfer is going on, you give another request to write data to the flash drive. If the second request doesn’t write protect the USB, then try sending a third command, all at the same time of course, and this will certainly write protect the drive.

#2 The USB is write protected by design. Meaning the content owner (person who put data on the drive) made the stick read only. Read only is another way of saying write protected.

USB Write Protectedv

How you make a working USB stick write protected is sending a

vendor command to the controller and turning off the SCSI write command. Understand, the IC chip on a USB stick is called the controller and it’s a chip which controls the read and write process between the USB memory and the host computer it is connected to. The SCSI write command (Small Computer System Interface) is unique to each USB controller on the market so there is no universal command. We get visitors emailing us at least once a week asking about software to set the write protection, well since each USB controller has their own command this is why you will never see a universal software solution. Sorry folks. does make a USB stick where you can turn on and off the USB write protection through software. The company offers a USB stick and a command line tool to do the function. The command line tool is a small utility program that runs in the background and only works when asked to do a specific task. A programmer may code in a process with in their software to turn on and off the USB write protection. This is really nice for embedding the code into a third party software program.

For example, let us say you have a software package which is distributed on USB media. It is important the company write protect the flash drive because A) you don’t want to spread any viruses and B) you don’t want a third party messing with your software and saving the change to the USB stick. Using the Nexcopy lock utility, you can embed the ability to unlock the drive, update the software and re-lock the drive remotely. This combination gives the security of a write protected USB stick yet the ability to update the software at a later date.

Will there ever be a universal software tool to set the USB write protection? No.

Why? There are hundreds of companies who make USB controllers. Each company has their own set of commands, in addition the NAND memory market moves so quickly it’s impossible to log all the controller companies, their vendor commands, and the NAND memory the controllers are compatible with.

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Rich Gates

Administator for started in 2004 with the concept of providing USB information for everything USB related. At the time, USB was gaining momentum and every day new products, articles and news became published. Today, the site is focused on bringing technical information, tricks and hacks to USB related products. The site does publish off topic information as well, to keep the variety up. Please visit the footer area of any page if you or your company is interested in article or product placement via purchased advertising.

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