If you plan on developing a plugin or contributing to Matomo (formerly Piwik) Core your code must be secure.
This guide contains a list of methods to combat certain vulnerabilities. Follow all of them when working on your plugin or contribution.
XSS is the injection of malicious scripts (e.g. JavaScript) into the user interface. It can allow attackers to gain control of the application or steal information.
Attackers can achieve that either by:
In your PHP code, if you need access to a variable in $_GET or $_POST, always use Common::getRequestVar().
getRequestVar() will sanitize the request variable. If an attacker passes a string containing <script>...</script>, it will be sanitized to <script>...</script>. This will help to avoid accidentally embedding unescaped text in HTML output.
For text you know may contain special characters or if you need to output text in a format that doesn't need XML/HTML sanitization (like JSON), call Piwik::unsanitizeInputValues() to undo the sanitization.
Note: You can sanitize text that isn't in a request parameter by using Piwik::sanitizeInputValues().
It's important to use the correct escaping strategy depending on where you are printing a value. For example, when printing a value in an HTML attribute like "title" or "label", then we need to use an |e('html_attr') escaping strategy. Other escaping strategies are js, css, url and html (which is the default strategy).
|raw sparingly in Twig templatesWhen writing Twig templates, try to avoid using the |raw filter when possible. As an alternative, put the HTML you want to reuse in a separate template and {% include %} it.
If you do use |raw, make sure what you're inserting has been properly escaped.
If you have to use the |raw filter you may want to think about using the |rawSafeDecoded filter which may be more secure.
jQuery.html()In your JavaScript, be careful when using the $.html method to insert HTML into the DOM. Make sure the string you are inserting came from Matomo and has been escaped.
If you know that the text you're inserting shouldn't be HTML, then do not use $.html(), instead use $.text() or $.val(). For example:
var ajaxData = getDataFromAjax();
$('#someLabel').text(ajaxData.labelToUse);
To escape strings in JavaScript you may use the helper method piwikHelper.escape for example:
var safeString = piwikHelper.escape( userInputUnsafeString );
$('#someLabel').text( safeString );
Content Security Policy is set by default in Matomo (since Matomo 4.6.0) and plugins can modify the CSP as needed using $this->securityPolicy methods in the controller, for example:
$this->securityPolicy->addPolicy('image-src', 'self');
Or using dependency injection by creating a plugins/MyPlugin/config/config.php like this to apply the change to every UI request instead of only a specific request:
return array(
\Piwik\View\SecurityPolicy::class => DI\decorate(function ($previous) {
/** @var \Piwik\View\SecurityPolicy $previous */
if (!\Piwik\SettingsPiwik::isMatomoInstalled()) {
return $previous;
}
$previous->addPolicy('default-src', 'my-cdn.example.com');
return $previous;
}),
);
Consider using the default, or a more restrictive CSP if possible which will protect against certain XSS attacks.
CSRF attacks is where an attacker make a Matomo user perform an action unwillingly. To achieve that, the attacker sends a link to the user. The link could, for example, point to a Matomo controller method that changes the user's password, or delete a site.
This attack can be prevented with the following technique:
In every controller method you create that changes Matomo settings, changes a user's settings or does some other admin level function, call the Controller::checkTokenInUrl() method. For example:
// method in a controller
public function doSomeAdminStuff()
{
$this->checkTokenInUrl();
// ...
}
In every API method that executes some admin level function, make sure to check for the proper user permissions by calling one of the Piwik::check... methods. For example:
// method in an API class
public function changeSettingsForUser($userLogin)
{
Piwik::checkUserHasSuperUserAccessOrIsTheUser($userLogin);
}
Your JavaScript should send the token_auth to controller and API methods that need it, but you should make sure the token_auth never appears in the URL. This way, it will never be saved or cached by the browser.
To keep the token_auth out of a browser cache, you can use POST requests.
SQL Injection is the manipulation of the application's SQL queries by injecting malicious SQL statements. Attackers can inject malicious SQL through inputs of the application: form fields, request parameters, …
For example, if an application builds an SQL query like this:
$sql = 'SELECT * from mytable where id = ' . $_GET['id'];
An attacker could pass "1 OR 1" for the id URL parameter. This would cause the following query to be executed: SELECT * from mytable where id = 1 OR 1, which would output every row of mytable.
SQL injection can be prevented by doing one thing:
When writing SQL statements, use SQL prepared statements instead of directly inserting variables into your statement. SQL prepared statements means using placeholders in your SQL queries.
In other words, don't do this:
$idSite = Common::getRequestVar('idSite');
// DON'T DO THIS!!
$sql = "SELECT * FROM " . Common::prefixTable('site') . " WHERE idsite = " . $idSite;
$rows = Db::query($sql);
Instead, do this:
$idSite = Common::getRequestVar('idSite');
$sql = "SELECT * FROM " . Common::prefixTable('site') . " WHERE idsite = ?";
$rows = Db::query($sql, array($idSite));
Remote File Inclusion is the inclusion and execution of source code that is not part of the webapp. It happens in PHP with include or require statements that use a path determined by the user.
In Matomo, the best way to prevent remote file inclusion attacks is to just never require/include files using data from the user. Instead, put logic in classes that can be loaded by Matomo's autoloader and instantiate/use different classes based on data obtained from the user. In other words, don't do this:
$clientToUse = Common::getRequestVar('seoClient');
// DON'T DO THIS!!
require_once PIWIK_INCLUDE . '/plugins/MyPlugin/Clients/' . $clientToUse . '.php';
$client = new $clientToUse();
// ... use $client ...
Instead, do this:
$clientToUse = Common::getRequestVar('seoClient');
if ($clientToUse == 'mySeoProvider') {
$client = new Clients\MySeoProvider();
} else if ($clientToUse == 'myOtherSeoProvider') {
$client = new Clients\MyOtherSeoProvider();
} else {
throw new Exception("Invalid SEO provider client: $clientToUse!");
}
// ... use $client ...
Here are some other coding guidelines that will help make your code more secure:
PHP files should start with a <?php tag that is never closed.
Use the .php extension for all your PHP scripts.
Avoid executing php code using one of the following functions: eval, exec, passthru, system, popen or preg_replace (with the "e" modifier).
Make sure that accessing your files directly doesn't execute any code that could have an impact on your Matomo install.
Make sure your code doesn't rely on register_globals set to On. Note: PHP5 sets register_globals to Off by default.
For timing attack safe equal comparisons use Common::hashEquals() method
If your plugin has admin functionality (functionality only an administrator or the super user can use) then your plugin's Controller must extend Piwik\Plugin\ControllerAdmin.
By no means is below a complete checklist. You'll always be required to still think of any other case something can be used in a way we don't want it to be used. It's only a list for the most common checks.
Common::hashEquals is usedrel="noreferrer noopener" (although newer browser versions add this automatically). The noopener is needed for security reasons. The noreferrer for privacy reasons. See rel=noreferrer and rel=noopenerunserialize is unsafe for user input. Consider using Common::safe_unserialize or for user input possibly JSON insteadfile_get_contents can be unsafe when eg a protocol phar:// can be passed to itPiwik_ShouldPrintBackTraceWithMessage()===true). Be aware that echoing an \Exception or using it as a string when logging (echo $exception) can cause the exception to be indirectly appear with a stack trace.