Sql = “SELECT * FROM Customers WHERE CustomerId = new INTO STATEMENT IN ASP.NET:
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TxtSQL = “INSERT INTO Customers (CustomerName,Address,City) following examples shows how to build parameterized queries in some common web languages. TxtNam = getRequestString(“CustomerName”) The SQL engine checks each parameter to ensure that it is correct for its column and are treated literally, and not as part of the SQL to be executed. TxtSQL = “SELECT * FROM Users WHERE UserId = that parameters are represented in the SQL statement by a marker. SQL parameters are values that are added to an SQL query at execution time, in a controlled manner. To protect a web site from SQL injection, you can use SQL parameters. How to Prevent SQL Injection Using SQL Parameters for Protection SELECT * FROM Users WHERE UserId = 105 DROP TABLE Suppliers The valid SQL statement would look like this: Result SELECT * FROM Users DROP TABLE Suppliers The SQL statement below will return all rows from the “Users” table, then delete the “Suppliers” table. Most databases support batched SQL statement.Ī batch of SQL statements is a group of two or more SQL statements, separated by semicolons. SQL Injection Based on Batched SQL Statements The SQL above is valid and will return all rows from the “Users” table, since OR “”=”” is always TRUE.
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The code at the server will create a valid SQL statement like this: Result
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SELECT * FROM Users WHERE Name =”John Doe” AND Pass =”myPass”Ī hacker might get access to user names and passwords in a database by simply inserting ” OR “”=” into the user name or password text box: Sql = ‘SELECT * FROM Users WHERE Name =”‘ + uName + ‘” AND Pass =”‘ + uPass + ‘”‘ Result UPass = getRequestString(“userpassword”) Here is an example of a user login on a web site: SQL Injection Based on “”=”” is Always True SELECT UserId, Name, Password FROM Users WHERE UserId = 105 or 1=1 Ī hacker might get access to all the user names and passwords in a database, by simply inserting 105 OR 1=1 into the input field. The SQL statement above is much the same as this: The SQL above is valid and will return ALL rows from the “Users” table, since OR 1=1 is always TRUE.ĭoes the example above look dangerous? What if the “Users” table contains names and passwords? Then, the SQL statement will look like this: If there is nothing to prevent a user from entering “wrong” input, the user can enter some “smart” input like this: The original purpose of the code was to create an SQL statement to select a user, with a given user id. SQL Injection Based on 1=1 is Always True The rest of this chapter describes the potential dangers of using user input in SQL statements. TxtSQL = “SELECT * FROM Users WHERE UserId = ” + txtUserId The variable is fetched from user input (getRequestString): Example
Look at the following example which creates a SELECT statement by adding a variable (txtUserId) to a select string. SQL injection usually occurs when you ask a user for input, like their username/userid, and instead of a name/id, the user gives you an SQL statement that you will unknowingly run on your database.
SQL injection is the placement of malicious code in SQL statements, via web page input. SQL injection is one of the most common web hacking techniques. SQL injection is a code injection technique that might destroy your database.
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