USB Thumb Drive - With Physical Write Lock Switch

USB Thumb Drive - With PHYSICAL Write Protect Switch

Yes, they do make these. (For example: Kanguru FlashBlu30) My question is: Can you reformat these if the write protect switch is active? (I'm hoping not!)

If I owned one I would just verify this myself, but all my thumbs are dumb. :)

Thanks!!

-mpm

Reply to
mpm
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You might investigate how it works. I read somewhere that some SD card locks are a "suggestion" and can be easily ignored by malware. Don't remember ever seeing a USB thumb drive with a lock, so don't know if it's relevant there.

Reply to
mike

Yes, iirc the write protect switch on a SD card is just a mechanical bit of plastic that activates a switch on the socket, which if it is wired up to an IO pin of the processor that is writing to the card, might be used by the software to decide whether to write to the card or not. If the software is infested with malware then the write protect switch will of course be ignored. I think they didn't even wire up the switch on the raspberry pi.

SD cards contain quite powerful processors, and can be re-programmed to do all sorts of things. e.g. if the blocks are read out in a certain sequence that is characteristic of how a given device mounts the filesystem, then different contents could be delivered, so you could make it appear to contain different files depending on whether it was being accessed from Linux, windows or a forensic copying machine used to gather evidence.

formatting link

Reply to
Chris Jones

Ok, but it doesn't have to be that complex.

Why would anybody want to prevent writes to a device? Most likely to prevent ACQUISITION of malware from an infected computer. That doesn't require any cooperation from the memory device other than accepting a file transfer. How many people disable AutoPlay? That makes it easier to acquire malware from an infected thumb drive. Again no cooperation required from the drive, other than letting the computer mount it.

Reply to
mike

Just as a reminder, my question concerns thumb drives, not SD cards.

Reply to
mpm

yes, but... SD cards (and SDHC and SDXC) obey a lot of extra (standard) rules that USB mass storage doesn't need to.

SD (by specification) has locks. And, an SD reader that takes a MicroSD card sometimes looks just like a thumb drive. Glue a cap on it, and it IS a thumb drive.

Reply to
whit3rd

But all this avoids my point: "check out how it works to verify it meets your requirements."

If the device only SUGGESTS that it should not be written, it may not always be able to reject improper advances or do what you expect...whatever that is. IN the current frenzy, "I said no!" doesn't prevent rape.

Reply to
mike

The difference is that "no" defines rape.

Reply to
krw

ABSOLUTELY, but it does not PREVENT rape...by definition.

A memory stick could easily say no to a cooperative and benign request. It's a very different thing to PREVENT write access in the face of determination from the source of that write.

If it's possible to put a mechanical switch to disconnect the write line to the memory, that might be a reliable method. Anything less invites a hack to circumvent it. I don't know how these switches work. I merely suggest that you should VERIFY that they do what you want.

We don't know what the OP wants. Statistically, one would surmise that it's to prevent writes from things evil. I contend that ALL things are evil until proven otherwise...and most of those can be turned evil in an instant by malicious sources.

Bottom line...don't stick it where it don't belong.

Reply to
mike

But ignoring the switch doesn't mean the write was malicious.

That's a lousy way to live one's life.

...if you expect it back.

Reply to
krw

I have an elderly M-FLash PRUB01(S) 1GB USB memory stick with write protect switch. When switched to write protect then Windows refuses to Format it. I do not know if the enforcement is the hardware within the device or just software honoring the switch status.

HTH

piglet

Reply to
piglet

Thanks! I suspect it is the USB memory stick itself preventing the re-format (as well as any other writing to the card) as long as the physical write protect switch is engaged.

Reply to
mpm

On Sunday, November 12, 2017 at 9:33:38 PM UTC-5, mpm wrote: ...

I wanted to follow-up and close out this thread:

Happy to report that "Yes", the KanguruBlu30 thumb drive with physical write-protect switch (mentioned earlier) does indeed work exactly as advertised.

Not shilling for them - just happy that it works.

With the switch set to the "Lock" position, further writes to the thumb-drive are not possible. It must be unlocked to write.

Reply to
mpm

I'd be interested in how you verified that. Easy to understand how further writes from a cooperating OS/Program would be blocked. What about non-cooperating Programs that circumvent standard procedures/methods...AKA malware?

Reply to
mike

Depends on what you mean by "active". If the write protect is set to prevent writing to the device then it does what it says on the tin.

You can get sD cards with write protect switches more easily and put them in a USB sD carrier if you want something that will hold data and resist attempts by a user to do stupid things with it. Any external switch can always be put into the wrong state by a customer.

--
Regards, 
Martin Brown
Reply to
Martin Brown

The contacts of that write protect switch are not in the SD card, they are in the socket. They are not even wired up on the Raspberry Pi IIRC, and can be ignored by software on most devices where they are wired up. In the best case (contacts are wired up), that may help against a stupid user who deliberately tries to write to the card, but it won't necesarily help against a user (stupid or otherwise) who plugs the card into a malware-infested machine.

Reply to
Chris Jones

Verified by trying to write, format, etc.. on several PC's and even some te st equipment (some of which runs WindowsCE, etc.. , though). But also test ed on a Linux box and an Apple iOS.

Behaves like a normal thumb-drive when the switch is set to unlock. Will not write or format when set to "lock", but does enumerate (i.e., is r ecognized by and attaches to the host normally).

Reply to
mpm

I thought about that too, and may need to research it further. Yes, I could find a SD reader that enforces the lock switch, and then make the combination (card + reader) unavailable to the end-user, perhaps by using a short USB-USB cable. The downside is I would have to power the reader.

With the USB approach, I don't.

Reply to
mpm

Firstly, there are SOFTWARE write-protect switches available (and password, and other features) in the SD card specifications. Second 'power the reader' for most SD card readers means plugging it into a USB port; it' happens whenever you make the data connection.

Reply to
whit3rd

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