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A classification of SQL injection attacking vector as of 2010. In computing, SQL injection is a code injection technique used to attack data-driven applications, in which malicious SQL statements are inserted into an entry field for execution (e.g. to dump the database contents to the attacker).
An SQL injection takes advantage of SQL syntax to inject malicious commands that can read or modify a database or compromise the meaning of the original query. [13] For example, consider a web page that has two text fields which allow users to enter a username and a password.
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
A function is bijective if it is both injective and surjective. A bijective function is also called a bijection or a one-to-one correspondence (not to be confused with one-to-one function, which refers to injection). A function is bijective if and only if every possible image is mapped to by exactly one argument. [1]
The technique transforms an application SQL statement from an innocent SQL call to a malicious call that can cause unauthorized access, deletion of data, or theft of information. [ 3 ] One way that DAM can prevent SQL injection is by monitoring the application activity, generating a baseline of “normal behavior”, and identifying an attack ...
Single quotes, double quotes, backslashes and null characters in all user-supplied data all have a backslash prepended to them before being passed to the script in the $_GET, $_REQUEST, $_POST and $_COOKIE global variables. Developers can then in theory use string concatenation to construct safe SQL queries with data provided by the user.
Referential integrity is a property of data stating that all its references are valid. In the context of relational databases, it requires that if a value of one attribute (column) of a relation (table) references a value of another attribute (either in the same or a different relation), then the referenced value must exist. [1]