Summary

• Do be strict about what you will accept as a valid filename.

• Do not blindly accept a filename thinking it represents a valid file especially on server platforms.

• Consider storing temporary files in the users temporary directory, not in a shared location. This has an added benefit of making it easier to run your application in least privilege, because the user has full access to their private directory. However, in many cases, only elevated accounts such as administrator and root can access system temporary directories.