==== Use pre-approved folders

Create a special folder where untrusted data should be stored. This folder
should be classified as untrusted and have the following characteristics:

* It should have specific read and write permissions that belong to the right people or organizations.
* It should have a size limit or its size should be monitored.
* It should contain backup copies if it contains data that belongs to users.

This folder should not be located in `/tmp`, `/var/tmp` or in the Windows
directory `%TEMP%`. +
These folders are usually "world-writable", can be manipulated, and can be
accidentally deleted by the system.

Also, the original file names and extensions should be changed to controlled
strings to prevent unwanted code from being executed based on the file names.
