Friday, June 1, 2012

How to secure database passwords in PHP?

When a PHP application makes a database connection it of course generally needs to pass a login and password. If I'm using a single, minimum-permission login for my application, then the PHP needs to know that login and password somewhere. What is the best way to secure that password? It seems like just writing it in the PHP code isn't a good idea.

Source: Tips4all


  1. Several people misread this as a question about how to store passwords in a database. That is wrong. It is about how to store the password that lets you get to the database.

    The usual solution is to move the password out of source-code into a configuration file. Then leave administration and securing that configuration file up to your system administrators. That way developers do not need to know anything about the production passwords, and there is no record of the password in your source-control.

  2. If you're hosting on someone else's server and don't have access outside your webroot, you can always put your password and/or database connection in a file and then lock the file using a .htaccess:

    <files mypasswdfile>
    order allow,deny
    deny from all

  3. Store them in a file outside web root.

  4. For extremely secure systems we encrypt the database password in a configuration file (which itself is secured by the system administrator). On application/server startup the application then prompts the system administrator for the decryption key. The database password is then read from the config file, decrypted, and stored in memory for future use. Still not 100% secure since it is stored in memory decrypted, but you have to call it 'secure enough' at some point!

  5. if it is possible to create the database connection in the same file where the credentials are stored. Inline the credentials in the connect statement.

    mysql_connect("localhost", "me", "mypass");

    Otherwise it is best to unset the credentials after the connect statement, because credentials that are not in memory, can't be read from memory ;)

    mysql_connect("localhost", $db_user, $db_pass);
    unset ($db_user, $db_pass);

  6. Your choices are kind of limited as as you say you need the password to access the database. One general approach is to store the username and password in a seperate configuration file rather than the main script. Then be sure to store that outside the main web tree. That was if there is a web configuration problem that leaves your php files being simply displayed as text rather than being executed you haven't exposed the password.

    Other than that you are on the right lines with minimal access for the account being used. Add to that

    Don't use the combination of username/password for anything else
    Configure the database server to only accept connections from the web host for that user (localhost is even better if the DB is on the same machine) That way even if the credentials are exposed they are no use to anyone unless they have other access to the machine.
    Obfuscate the password (even ROT13 will do) it won't put up much defense if some does get access to the file, but at least it will prevent casual viewing of it.


  7. Put the database password in a file, make it read-only to the user serving the files.

    Unless you have some means of only allowing the php server process to access the database, this is pretty much all you can do.

  8. If you're talking about the database password, as opposed to the password coming from a browser, the standard practice seems to be to put the database password in a PHP config file on the server.

    You just need to be sure that the php file containing the password has appropriate permissions on it. I.e. it should be readable only by the web server and by your user account.

  9. Best way is to not store the password at all!
    For instance, if you're on a Windows system, and connecting to SQL Server, you can use Integrated Authentication to connect to the database without a password, using the current process's identity.

    If you do need to connect with a password, first encrypt it, using strong encryption (e.g. using AES-256, and then protect the encryption key, or using asymmetric encryption and have the OS protect the cert), and then store it in a configuration file (outside of the web directory) with strong ACLs.

  10. The most secure way is to not have the information specified in your PHP code at all.

    If you're using Apache that means to set the connection details in your httpd.conf or virtual hosts file file. If you do that you can call mysql_connect() with no parameters, which means PHP will never ever output your information.

    This is how you specify these values in those files:

    php_value mysql.default.user myusername
    php_value mysql.default.password mypassword
    php_value server

    Then you open your mysql connection like this:

    $db = mysqli_connect();

    Or like this:

    $db = mysqli_connect(ini_get(”mysql.default.user”),

  11. I think the OP means the database password.

    Unless someone gains access to your server via FTP or SSH (in which case you're already buggered), I wouldn't worry about storing passwords in plaintext in PHP files. Most PHP applications I've seen do it that way, for example phpbb.

  12. An additional trick is to use a PHP separate configuration file that looks like that :

    <?php exit() ?>


    Plain text data including password

    This does not prevent you from setting access rules properly. But in the case your web site is hacked, a "require" or an "include" will just exit the script at the first line so it's even harder to get the data.

    Nevertheless, do not ever let configuration files in a directory that can be accessed through the web. You should have a "Web" folder containing your controler code, css, pictures and js. That's all. Anything else goes in offline folders.

  13. Storing something outside the webroot which can't be accessed from the web is a smart move. Then require() this file and use this with the mysql_connect . On my webhotel I have this file where all of my subdomain-folders are. So I've created a function that returns the password because I use multiple database-accounts.

    function returnDatabasePassword($username) {
    $passwords = array(
    'db_username' => 'password',
    'db_username2' => 'anotherPassword'
    return $passwords[$username];

  14. Just putting it into a config file somewhere is the way it's usually done. Just make sure you A) disallow database access from any servers outside your network, B) take care not to accidentally show the password to users (in an error message, or through PHP files accidentally being served as HTML, etcetera.)

  15. If you are using PostgreSQL, then it looks in ~/.pgpass for passwords automatically. See the manual for more information.

  16. It might be worth taking a look at Chris Shiflett's solution. He suggests setting credentials in environment variables in a separate file, not accessible by apache.

  17. To be totally secure, you'll need to set up an ssl connection, otherwise anyone on your network can still sniff the password you type.

  18. MD5ing both the real password and the user submitted one, then comparing the two is a generally accepted way of avoiding storing plaintext passwords anywhere.