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Heutzutage sind Datenbanken die Hauptkomponenten jeder Webbasierten Applikation, aufgrund welcher Websites verschiedene dynamische Inhalte anbieten können. Nachdem heikle oder geheime Informationen in solch einer Datenbank gespeichert werden können, sollten Sie deren Schutz ernsthaft bedenken.
Um Informationen zu bekommen oder zu speichern, müssen Sie eine legitime Abfrage senden, das Ergebnis holen, und die Verbindung schließen. Heutzutage ist die allgemein verwendete Abfragesprache für solche Interaktionen die Structured Query Language (SQL). Sehen Sie, wie sich ein Angreifer an einer SQL Abfrage zu schaffen machen kann.
Sie werden merken, dass PHP Ihre Datenbank alleine nicht schützen kann. Die folgenden Abschnitte sind eine Einführung in die Grundlagen, wie man innerhalb von PHP Skripten auf Datenbanken zugreift und diese manipuliert.
Denken Sie an diese einfache Regel: tief gestaffelte Verteidigung. Je mehr Platz Sie den Maßnahmen zum Schutz Ihrer Datenbank geben, desto geringer ist die Wahrscheinlichkeit, dass ein Angreifer Erfolg hat, und gespeicherte Geheiminformationen aufdeckt oder missbraucht. Gutes Design des Datenbankschemas und die Applikation wird mit Ihren größten Befürchtungen fertig.
SQL injection could be prevented by inserting only base64_encoded data into the data base. Before searching the data base for a certain value or string base64_encode the search string and then start the query.
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.
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.
<?php
$getal1 = 5.5;
$getal2 = 2.0;
function printDeling() {
$resultaat = global $getal1 / global $getal2;
return $resultaat;
}
function printVermenigvuldiging() {
$resultaat = global $getal1 * global $getal2;
return $resultaat;
}
function printSom() {
$resultaat = global $getal1 + global $getal2;
return $resultaat;
}
function printAftrekking() {
$resultaat = global $getal1 - global $getal2;
return $resultaat;
}
(printDeling()>=7) ? print "<font color=\"green\"> printDeling()</font>" : print "<font color=\"red\"> printDeling()</font>" ;
?>
Encrypting user input doesn't do much to guard against SQL injection attacks. Naturally, you want to encrypt sensitive information across the wire, but if a user puts in malicious data into an input field, any encryption scheme will just dutifully unpack it at the other and and still run the SQL injection hack if you haven't guarded against it.
Encryption is not magic pixie dust to sprinkle on things to make them more secure.
On a database design point of view, you should make sure that you design databases in a manor that any query run from them need minimal input from the user and if it requires user input, that you encrypt where possible.
I would say one of the best ways to guard against SQL injection is to use the excellent PEAR DB package. If you prepare() and execute() your queries, PEAR will automagically addslashes and handle the query depending on your RDBMS. And of course, for repeatable queries prepare and execute will give you a bit of a readability and speed increase.
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