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I am new to databases and security.

I am planning to put up a website.

I've read that sql-injection vulnerabilities can be very dangerous since the server might leak user passwords and credit-card information.

Are there any steps that I need to follow to prevent SQL injection vulnerabilities?

I was going through a wiki on sql-injection, but I didn't understood the following query:

SELECT * FROM users WHERE name = '" + userName + "';
  • You may want to add more information about what you don't understand about the query. Is it the double-quotes you don't understand, or the entire query? If you are new to databases and security, and are concerned about SQL injection vulnerabilities, you would do well to take a course, or better yet, hire a professional. SQL Injection is a very complex topic and not easily covered in a simple question and answer format such as this. – Max Vernon Sep 27 '12 at 2:45
  • If you are worried about leaking credit card information, you really, really need to hire a security and database professional. – Max Vernon Sep 27 '12 at 2:46
  • @MaxVernon, it's the combination of the single quote and the double quote that is confusing me and the '+'. – Ankit Sep 27 '12 at 5:57
  • The double-quotes prevent escaping from the intended query by using a single quote embedded within the userName variable. Consider what would happen if userName was filled in by the user as: ';DROP TABLE users + ' - this would have the unfortunate side effect of deleting the Users table, with no warning, and no way of preventing it. The double-quotes encapsulate the bad query, essentially forcing it to be evaluated as part of the WHERE clause. – Max Vernon Sep 27 '12 at 6:02
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you better use prepared statement from your programming source code, e.g. for PHP use PDO's prepare statement!

Check this - https://stackoverflow.com/questions/60174/best-way-to-prevent-sql-injection-in-php

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I used a private function that vetted all the parameters passed into my services (Models in today's parlance). In a large application you might as well make it a 'global' function that all your scripts/models access when you're accepting any parameters from your frontend
eg

private function protectMySQL($myParam)
{
    $myParam = stripslashes($myParam);
    $myParam = mysql_real_escape_string($myParam);
    return $myParam;
}

and then in each function

public function setMonthlyData($companyID, $userID, $resultArr)
{
    require_once("vo/Object.php");
    $myResponseObj = new Object();

    $myCompanyID = $this -> protectMySQL($companyID);  //vet $companyID
    $myUserID = $this -> protectMySQL($userID);        //vet $userID

    //.....etc
    //execute query using parameters
    //then return the result 
}

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