This disclosure describes, generally, methods and systems for self defending and repairing a database. The method includes monitoring, at a database server, code modifications to a database management application. The database management application is configured to maintain the database. The method further includes determining that a code modification has occurred to the database management application. The method further includes checking the code modification for the presence of an authorization key, and in response to an invalid or non-existent authorization key, determining that the code modification is unauthorized. Further, the method includes quarantining the modified code in a secure storage location, and automatically accessing original code of the database management application and replacing the modified code with code from the original code of the database management application.