SunshinePHP Developer Conference 2015

Segurança de Bancos de Dados

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Hoje em dia, bancos de dados são componentes cardinais de qualquer aplicação web permitindo que websites forneçam conteúdo dinâmico variável. uma ves que informação muito sensível e/ou secreta pode ser guardada em um banco de dados, proteger seus bancos de dados é essencial.

Para retirar ou guardar qualquer informação, você precisa conectar-se ao banco de dados, enviar uma consulta (query) legítima, puxar o resultado e fechar a conexão. Atualmente, a linguagem mais usada para consulta nessa interação é a Structured Query Language (SQL). Veja como um atacante pode manipular uma consulta SQL.

Como você pode perceber, o PHP não pode proteger seu banco de dados sozinho. As seções a seguir tentam ser uma introdução básica em relação a como acessa e manipular banco de dados a partir de scripts PHP.

Mantenha em mente essa regra simples: defesa em profundidade. Quanto mais lugares você faz ações para aumentar a proteção do seu banco, menor a probabilidade de um atacante ter suceso em expor ou abusar de qualquer informação guardada. Bom desenho do esquema (schema) de banco de dados e da aplicação lida com seus maiores medos.

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User Contributed Notes 4 notes

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Anonymous
9 years ago
you can also chamge CHMOD for some file containing "user names" or "passwords"
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Chris Travers
2 years ago
Regarding where to put logic, it's really best not to be dogmatic about this.  Putting logic in the db can have some security advantages but it has other security gotchas (for example, SQL injection inside a stored procedure may be possible in some environments).  Similarly it can have some portability advantages and disadvantages.

The real question is that you want to ask what you want to be portable.  If you put it in the db, it becomes easier to integrate programs written in different development environments with a minimum of security gotchas.  If you put it in the application, then you have to create the interfaces on that level in middleware.  Both approaches are doable.  On the other hand if you are writing software you want to be deployable in MS SQL shops and Oracle shops, then you have to write portable SQL (avoiding gotchas) and put the logic in the application.

When we started rewriting the LedgerSMB codebase, we decided to move logic into the db because this would make it easier to retrofit security onto a very insecure codebase (by not trusting the application), and because we wanted to support languages other than Perl.  A few years later this is bearing fruit and indeed I am reading the manual because I am writing integration libraries in PHP.  I am not much of a PHP guy (I haven't programmed PHP since PHP 4.x) but I can write modules that let folks write code to interface securely with LedgerSMB's database logic.  You can think of the stored procedures as being named queries which are shared between applications, or as API's to the database.  But again, this approach is not universally applicable.

If portability between db's is not a major requirement, then I think the best approach is to do as much as possible in SQL queries and put those in the database.  A couple hundred lines of SQL can replace a couple thousand lines in Perl or PHP, and is fundamentally easier to debug.  Of course that won't work for everyone.
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x12code at yahoo dot com
7 years ago
About offloading business logic to views and queries facilitated by the database engine, I seek to avoid this as much as possible, and only do so when such would drastically improve efficiency and user response time.

For instance, where I am there is database staff and application staff. Trying to do analysis on existent applications can easily become a snipe hunt.

The database should be kept discreet as much as possible from the application, such that any database or database provider can easily be substituted with a minimum of cognitive effort on the part of the one setting up a new database. If functionality has been offloaded to the database, additional testing is required to make sure triggers and views were done correctly, again, and that they work right.

Also, keeping all business logic with the application allows all functionality and documentation to be readable in one place, which is invaluable when doing subsequent analysis on an existing application. The worst thing is to have functionality scattered here and there.

Keeping everything with the application means one group of people is responsible, as in my case, application staff. Fewer requests go back and forth. Remember, anytime someone else is brought into the picture, such as asking a DBA to create a view or trigger for you, that DBA must take responsibility over his or her work, with whatever requirements, causing more bureaucracy and administrative complexity.
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Dave Martin
7 years ago
The posting below is at the very best extremely POV.

There is no more reason to assume you would want to change database vendor than there is to assume you might want to port your php code to Java for example. In either case, its going to be a matter of luck where your business rules sit.

Even if your business rules sit in your application, SQL is NOT portable. Oracle outer joins and pivot queries for example, can look completely different to those in other vendors software (particularly from 8i or lower). This fact alone means that changing your DB vendor requires work on your business rules either in the database or in the application.

Having your rules in the database and keeping the sql in application simple, will at least keep the work in the database if you need to change DB vendor. If you have the rules in the PHP, you'll have to change both.
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