Some entropy is available in /cdrom/upgrade/random. Delete a sizable proportion from the start of the file before copying to /dev/urandom. This is more secure than copying bash to the same point! No it is not. Not unless /cdrom/upgrade/random pulls down entropy each time you gennerate the image, boot or whatever. Copying from a random point in a random file on the file-system is far more secure then the method you noted. Cheers.