In an earlier tip for sister site SearchSmallBizIT.com, I wrote about how to use policies to disable the use of USB block storage devices, such as "keychain" drives. In the past, this was done by disabling the driver that enables mass storage devices over USB. However, this approach wasn't very elegant, since it prevented all USB mass-storage devices from working at all.
Microsoft has introduced some changes into Windows XP Service Pack 2 that allow an administrator slightly more granular control over how USB removable drives are handled. A new storage device policy named WriteProtect makes it possible to prevent all removable USB drives from being written to. They will still act as readable devices, but they cannot be written to.
The new policy is set in the Registry in HKEY_LOCAL_MACHINESystem CurrentControlSetControlStorageDevicePolicies, as a DWORD named WriteProtect. When set to 1, all USB removable drives are write-protected. When set to 0 (or when the DWORD entry is removed entirely), USB drives can once again be written to. This is a machine-level setting and not a user-level setting.
Microsoft is apparently planning in the long run to make significant changes to the way USB mass storage works that will allow for very flexible control over removable devices. This might include allowing devices with certain authentication metadata to be read/written safely while disallowing others, which would allow for more granular security. Right now, only third-party applications such as SecureWave's Sanctuary Device Control allow this sort of thing.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter. Check out his Windows 2000 blog for his latest advice and musings on the world of Windows network administrators – please share your thoughts as well!
This was first published in September 2004