Wednesday, June 4, 2008

securing ntfs files and directories

How to protect NTFS files and directories

NTFS is the secure file system used by NT. Note that the program here can undermine NTFS security.

A. When you right click on a file in Explorer and select properties (or select Properties from the File menu) you are presented with a dialog box telling you information such as size, ownership etc. If the file/directory is on a NTFS partition there will be a security tab, and within that dialog, a permissions button. If you press that button you can grant access to users/groups on the resource at various levels.

There are six basic permissions

  • R - Read
  • W - Write
  • D - Delete
  • X - Execute
  • P - Change Permissions
  • O - Take Ownership

These can be assigned to a resource, however they are grouped for ease of use

  • No Access - User has no access to the resource
  • List - R User can view directory and filenames in directory
  • Read - RX User can read files in directory and execute programs
  • Add - WX User can add files to the directory, but cannot read or change the contents of the directory
  • Add & Read - RWX User has read and add permissions
  • Change - RWXD User has read, add, change contents and delete files
  • All - RWXDPO User can do anything she wants!

The permissions above can all be set on a directory, however this list is limited for a file, and permissions that can be set are only No Access, Read, Change and Full Control.

Another permission exists called "Special Access" (on a directory there will be two, one for files, one for directories), and from this you can set which of the basic permissions should be assigned.