In more severe cases, where the connection to the database server is made through an administrative account (such as “root” in MySQL or “sa” in MS SQL Server), the attacker can go as far as fully compromising the server’s operating system. In pages that display results, the same scheme can be used to display records and information that would otherwise be restricted to normal visitors, or to change the contents of records. With a little more effort, the same user can insert new user accounts, and delete or modify existing user accounts. This is one of the simplest forms of SQL injection. The snippet would possibly allow the user to bypass the login screen without having proper credentials. The resulting command would be the following, which would always return a non-empty dataset: SELECT * FROM users WHERE username = 'john' OR 1 = 1 - ' AND password='123456'
An average user inputting “john” as username and “123456” as password ( never use that password, by the way) would translate to the following command: SELECT * FROM users WHERE username = 'john' AND password = '123456'īut what if the user decides to try something else, such as the following: The command would then be sent to a database server, and the resulting dataset would determine whether the username and password correspond to a valid user account.
For instance, in PHP, the code would look something like the following: $sql_command = "select * from users where username = '". When users enter their credentials and press the “log in” button, the information is posted back to your web server, where it is combined with an SQL command. To see how it works, suppose you have a login form that takes a username and password: Any input channel can be used to send the malicious commands, including elements, query strings, cookies and files. SQL injection attacks are staged by sending malicious SQL commands to database servers through web requests.
Here’s what you need to know about SQL injection and how to protect your site against it. The scheme can be used by attackers to steal or tamper with data, hamper application functionality, and, in a worst-case scenario, gain administrative access to the database server. In a nutshell, SQL injection - also referred to as SQLi - uses vulnerabilities in a website’s input channels to target the database that sits in the backend of the web application, where the most sensitive and valuable information is stored. The scheme has been used to target well-known organizations and firms, including TalkTalk, VTech, Wall Street Journal and the U.S. Of all the attacks that can be staged against websites, SQL injection is among the most dangerous and pervasive kind, and has been used to deal real damage to businesses and organizations in the past year. Thanks to Chris Lienert and Guido Tonnaer for kindly helping to peer review this article.