SQL Injection: What is it?
SQL Injection is one of the many web attack mechanisms used by hackers to steal data from organizations. It is perhaps one of the most common application layer attack techniques used today. It is the type of attack that takes advantage of improper coding of your web applications that allows hacker to inject SQL commands into say a login form to allow them to gain access to the data held within your database.
In essence, SQL Injection arises because the fields available for user input allow SQL statements to pass through and query the database directly.
SQL Injection: An In-depth Explanation
Web applications allow legitimate website visitors to submit and retrieve data to/from a database over the Internet using their preferred web browser. Databases are central to modern websites – they store data needed for websites to deliver specific content to visitors and render information to customers, suppliers, employees and a host of stakeholders. User credentials, financial and payment information, company statistics may all be resident within a database and accessed by legitimate users through off-the-shelf and custom web applications. Web applications and databases allow you to regularly run your business.
SQL Injection is the hacking technique which attempts to pass SQL commands (statements) through a web application for execution by the backend database. If not sanitized properly, web applications may result in SQL Injection attacks that allow hackers to view information from the database and/or even wipe it out.
Such features as login pages, support and product request forms, feedback forms, search pages, shopping carts and the general delivery of dynamic content, shape modern websites and provide businesses with the means necessary to communicate with prospects and customers. These website features are all examples of web applications which may be either purchased off-the-shelf or developed as bespoke programs.
These website features are all susceptible to SQL Injection attacks which arise because the fields available for user input allow SQL statements to pass through and query the database directly.
Example of a SQLInjection Attack
Here is a sample basic HTML form with two inputs, login and password.
<form method="post" action="http://testasp.vulnweb.com/login.asp">
<input name="tfUName" type="text" id="tfUName">
<input name="tfUPass" type="password" id="tfUPass">
</form>
The easiest way for the login.asp to work is by building a database query that looks like this:
SELECT id
FROM logins
WHERE username = '$username'
AND password = '$password’
If the variables $username and $password are requested directly from the user's input, this can easily be compromised. Suppose that we gave "Joe" as a username and that the following string was provided as a password: anything' OR 'x'='x
SELECT id
FROM logins
WHERE username = 'Joe'
AND password = 'anything' OR 'x'='x'
As the inputs of the web application are not properly sanitised, the use of the single quotes has turned the WHERE SQL command into a two-component clause.
The 'x'='x' part guarantees to be true regardless of what the first part contains.
This will allow the attacker to bypass the login form without actually knowing a valid username / password combination!
SQL INJECTION CHEAT SHEET
LIve Example of a SQLInjection Attack
http://www.youtube.com/watch?v=WGkntart6WI&feature=related
