Read-only Thumbdrive in One Easy Step

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Read-only Thumbdrive in One Easy Step

By Adam Myers ⋅ June 13, 2008 ⋅

Tags: read only, registry editor, thumb drives, write protect

Some USB thumbdrives/memory sticks have a physical switch that can put the drive into read-only mode. When transferring files to an untrusted or compromised machine, a thumbdrive in read-only mode will prevent any data to be written to the drive, or corrupt data already on the drive. Unfortunately, not only are these thumbdrives difficult to find, they are also more expensive than their general purpose counterparts. But what if there was a way to do this cheapily and easily? Enough with the rhetorical questions, suffice to say there is and it involves using regedit.exe to edit the Windows Registry.

Standard disclaimers apply: editing the registry is an advanced skill that should be utilized cautiously and without distraction.

Click Start and in the Start Search box type regedit.exe
Traverse the Registry Editor navigation tree on the left hand side down to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\StorageDevicePolicies\(StorageDevicePolicies key may not exist, it’s safe to create)

Right click in the right hand side panel and select New->DWORD Value.
Name the string WriteProtect and assign it a value of 1

That’s all there is to it. Of note, if a drive is already mounted you must remount it after making this registry change in order for it to take effect. While a bit cumbersome if you are toggling a thumbdrive between Read/Write and Read-Only often, it’s invaluable in certain situations - which is why you’ve probably came to this howto in the first place.