# Security ## Introduction This page details notes on how to ensure that we develop secure SilverStripe applications. See our "[Release Process](/misc/release-process#security-releases) on how to report security issues. ## SQL Injection The [coding-conventions](/misc/coding-conventions) help guard against SQL injection attacks but still require developer diligence: ensure that any variable you insert into a filter / sort / join clause has been escaped. See [http://shiflett.org/articles/sql-injection](http://shiflett.org/articles/sql-injection). ### Automatic escaping SilverStripe automatically escapes data in SQL statements wherever possible, through database-specific methods (see `[api:Database->addslashes()]`). For `[api:MySQLDatabase]`, this will be `[mysql_real_escape_string()](http://de3.php.net/mysql_real_escape_string)`. * Most `[api:DataList]` accessors (see escaping note in method documentation) * DataObject::get_by_id() * DataObject::update() * DataObject::castedUpdate() * DataObject->Property = 'val', DataObject->setField('Property','val') * DataObject::write() * DataList->byID() * Form->saveInto() * FormField->saveInto() * DBField->saveInto() Data is escaped when saving back to the database, not when writing to object-properties. Example: :::php // automatically escaped/quoted $members = Member::get()->filter('Name', $_GET['name']); // automatically escaped/quoted $members = Member::get()->filter(array('Name' => $_GET['name'])); // needs to be escaped/quoted manually $members = Member::get()->where(sprintf('"Name" = \'%s\'', Convert::raw2sql($_GET['name'])));
It is NOT good practice to "be sure" and convert the data passed to the functions below manually. This might result in *double escaping* and alters the actually saved data (e.g. by adding slashes to your content).
### Manual escaping As a rule of thumb, whenever you're creating raw queries (or just chunks of SQL), you need to take care of escaping yourself. See [coding-conventions](/misc/coding-conventions) and [datamodel](/topics/datamodel) for ways to cast and convert your data. * `SQLQuery` * `DataObject::buildSQL()` * `DB::query()` * `Director::urlParams()` * `Controller->requestParams`, `Controller->urlParams` * `SS_HTTPRequest` data * GET/POST data passed to a form method Example: :::php class MyForm extends Form { public function save($RAW_data, $form) { $SQL_data = Convert::raw2sql($RAW_data); // works recursively on an array $objs = Player::get()->where("Name = '{$SQL_data[name]}'"); // ... } } * `FormField->Value()` * URLParams passed to a Controller-method Example: :::php class MyController extends Controller { private static $allowed_actions = array('myurlaction'); public function myurlaction($RAW_urlParams) { $SQL_urlParams = Convert::raw2sql($RAW_urlParams); // works recursively on an array $objs = Player::get()->where("Name = '{$SQL_data[OtherID]}'"); // ... } } As a rule of thumb, you should escape your data **as close to querying as possible**. This means if you've got a chain of functions passing data through, escaping should happen at the end of the chain. :::php class MyController extends Controller { /** * @param array $RAW_data All names in an indexed array (not SQL-safe) */ public function saveAllNames($RAW_data) { // $SQL_data = Convert::raw2sql($RAW_data); // premature escaping foreach($RAW_data as $item) $this->saveName($item); } public function saveName($RAW_name) { $SQL_name = Convert::raw2sql($RAW_name); DB::query("UPDATE Player SET Name = '{$SQL_name}'"); } } This might not be applicable in all cases - especially if you are building an API thats likely to be customized. If you're passing unescaped data, make sure to be explicit about it by writing *phpdoc*-documentation and *prefixing* your variables ($RAW_data instead of $data). ## XSS (Cross-Site-Scripting) SilverStripe helps you guard any output against clientside attacks initiated by malicious user input, commonly known as XSS (Cross-Site-Scripting). With some basic guidelines, you can ensure your output is safe for a specific use case (e.g. displaying a blog post in HTML from a trusted author, or escaping a search parameter from an untrusted visitor before redisplaying it).
Note: SilverStripe templates do not remove tags, please use [strip_tags()](http://php.net/strip_tags) for this purpose or [sanitize](http://htmlpurifier.org/) it correctly.
See [http://shiflett.org/articles/foiling-cross-site-attacks](http://shiflett.org/articles/foiling-cross-site-attacks) for in-depth information about "Cross-Site-Scripting". ### What if I can't trust my editors? The default configuration of SilverStripe assumes some level of trust is given to your editors who have access to the CMS. Though the HTML WYSIWYG editor is configured to provide some control over the HTML an editor provides, this is not enforced server side, and so can be bypassed by a malicious editor. A editor that does so can use an XSS attack against an admin to perform any administrative action. If you can't trust your editors, SilverStripe must be configured to filter the content so that any javascript is stripped out To enable filtering, set the HtmlEditorField::$sanitise_server_side [configuration](/topics/configuration) property to true, e.g. HtmlEditorField::config()->sanitise_server_side = true The built in sanitiser enforces the TinyMCE whitelist rules on the server side, and is sufficient to eliminate the most common XSS vectors. However some subtle XSS attacks that exploit HTML parsing bugs need heavier filtering. For greater protection you can install the [htmlpurifier](https://github.com/silverstripe-labs/silverstripe-htmlpurifier) module which will replace the built in sanitiser with one that uses the [HTML Purifier](http://htmlpurifier.org/) library. In both cases, you must ensure that you have not configured TinyMCE to explicitly allow script elements or other javascript-specific attributes. ##### But I also need my editors to provide javascript It is not currently possible to allow editors to provide javascript content and yet still protect other users from any malicious code within that javascript. We recommend configuring [shortcodes](/reference/shortcodes) that can be used by editors in place of using javascript directly. ### Escaping model properties `[api:SSViewer]` (the SilverStripe template engine) automatically takes care of escaping HTML tags from specific object-properties by [casting](/topics/datamodel#casting) its string value into a `[api:DBField]` object. PHP: :::php class MyObject extends DataObject { private static $db = array( 'MyEscapedValue' => 'Text', // Example value: not bold 'MyUnescapedValue' => 'HTMLText' // Example value: bold ); } Template: :::php The example below assumes that data wasn't properly filtered when saving to the database, but are escaped before outputting through SSViewer. ### Overriding default escaping in templates You can force escaping on a casted value/object by using an [escape type](/topics/datamodel) method in your template, e.g. "XML" or "ATT". Template (see above): :::php ### Escaping custom attributes and getters Every object attribute or getter method used for template purposes should have its escape type defined through the static *$casting* array. Caution: Casting only applies when using values in a template, not in PHP. PHP: :::php class MyObject extends DataObject { public $Title = 'not bold'; // will be escaped due to Text casting $casting = array( "Title" => "Text", // forcing a casting 'TitleWithHTMLSuffix' => 'HTMLText' // optional, as HTMLText is the default casting ); public function TitleWithHTMLSuffix($suffix) { // $this->Title is not casted in PHP return $this->Title . '(' . $suffix. ')'; } } Template: :::php Note: Avoid generating HTML by string concatenation in PHP wherever possible to minimize risk and separate your presentation from business logic. ### Manual escaping in PHP When using *customise()* or *renderWith()* calls in your controller, or otherwise forcing a custom context for your template, you'll need to take care of casting and escaping yourself in PHP. The `[api:Convert]` class has utilities for this, mainly *Convert::raw2xml()* and *Convert::raw2att()* (which is also used by *XML* and *ATT* in template code). PHP: :::php class MyController extends Controller { private static $allowed_actions = array('search'); public function search($request) { $htmlTitle = '

Your results for:' . Convert::raw2xml($request->getVar('Query')) . '

'; return $this->customise(array( 'Query' => Text::create($request->getVar('Query')), 'HTMLTitle' => HTMLText::create($htmlTitle) )); } } Template: :::php

$HTMLTitle

Whenever you insert a variable into an HTML attribute within a template, use $VarName.ATT, no not $VarName. You can also use the built-in casting in PHP by using the *obj()* wrapper, see [datamodel](/topics/datamodel) . ### Escaping URLs Whenever you are generating a URL that contains querystring components based on user data, use urlencode() to escape the user data, not *Convert::raw2att()*. Use raw ampersands in your URL, and cast the URL as a "Text" DBField: PHP: :::php class MyController extends Controller { private static $allowed_actions = array('search'); public function search($request) { $rssRelativeLink = "/rss?Query=" . urlencode($_REQUEST['query']) . "&sortOrder=asc"; $rssLink = Controller::join_links($this->Link(), $rssRelativeLink); return $this->customise(array( "RSSLink" => Text::create($rssLink), )); } } Template: :::php RSS feed Some rules of thumb: * Don't concatenate URLs in a template. It only works in extremely simple cases that usually contain bugs. * Use *Controller::join_links()* to concatenate URLs. It deals with query strings and other such edge cases. ### Filtering incoming HTML from TinyMCE In some cases you may be particularly concerned about which HTML elements are addable to Content via the CMS. By default, although TinyMCE is configured to restrict some dangerous tags (such as `script` tags), this restriction is not enforced server-side. A malicious user with write access to the CMS might create a specific request to avoid these restrictions. To enable server side filtering using the same whitelisting controls as TinyMCE, set the HtmlEditorField::$sanitise_server_side config property to true. ## Cross-Site Request Forgery (CSRF) SilverStripe has built-in countermeasures against [CSRF](http://shiflett.org/articles/cross-site-request-forgeries) identity theft for all form submissions. A form object will automatically contain a `SecurityID` parameter which is generated as a secure hash on the server, connected to the currently active session of the user. If this form is submitted without this parameter, or if the parameter doesn't match the hash stored in the users session, the request is discarded. You can disable this behaviour through `[api:Form->disableSecurityToken()]`. It is also recommended to limit form submissions to the intended HTTP verb (mostly `GET` or `POST`) through `[api:Form->setStrictFormMethodCheck()]`. ## Casting user input When working with `$_GET`, `$_POST` or `Director::urlParams` variables, and you know your variable has to be of a certain type, like an integer, then it's essential to cast it as one. *Why?* To be sure that any processing of your given variable is done safely, with the assumption that it's an integer. To cast the variable as an integer, place `(int)` or `(integer)` before the variable. For example: a page with the URL paramaters *mysite.com/home/add/1* requires that ''Director::urlParams['ID']'' be an integer. We cast it by adding `(int)` - ''(int)Director::urlParams['ID']''. If a value other than an integer is passed, such as *mysite.com/home/add/dfsdfdsfd*, then it returns 0. Below is an example with different ways you would use this casting technique: :::php public function CaseStudies() { // cast an ID from URL parameters e.g. (mysite.com/home/action/ID) $anotherID = (int)Director::urlParam['ID']; // perform a calculation, the prerequisite being $anotherID must be an integer $calc = $anotherID + (5 - 2) / 2; // cast the 'category' GET variable as an integer $categoryID = (int)$_GET['category']; // perform a byID(), which ensures the ID is an integer before querying return CaseStudy::get()->byID($categoryID); } The same technique can be employed anywhere in your PHP code you know something must be of a certain type. A list of PHP cast types can be found here: * `(int)`, `(integer)` - cast to integer * `(bool)`, `(boolean)` - cast to boolean * `(float)`, `(double)`, `(real)` - cast to float * `(string)` - cast to string * `(array)` - cast to array * `(object)` - cast to object Note that there is also a 'SilverStripe' way of casting fields on a class, this is a different type of casting to the standard PHP way. See [casting](/topics/datamodel#casting). ## Filesystem ### Don't allow script-execution in /assets As all uploaded files are stored by default on the /assets-directory, you should disallow script-execution for this folder. This is just an additional security-measure to making sure you avoid directory-traversal, check for filesize and disallow certain filetypes. Example configuration for Apache2: ... php_flag engine off Options -ExecCGI -Includes -Indexes If you are using shared hosting or in a situation where you cannot alter your Vhost definitions, you can use a .htaccess file in the assets directory. This requires PHP to be loaded as an Apache module (not CGI or FastCGI). **/assets/.htaccess** php_flag engine off Options -ExecCGI -Includes -Indexes ### Don't allow access to .yml files Yaml files are often used to store sensitive or semi-sensitive data for use by SilverStripe framework (for instance, configuration and test fixtures). You should therefore block access to all yaml files (extension .yml) by default, and white list only yaml files you need to serve directly. See [Apache](/installation/webserver) and [Nginx](/installation/nginx) installation documentation for details specific to your web server ## Passwords SilverStripe stores passwords with a strong hashing algorithm (blowfish) by default (see [api:PasswordEncryptor]). It adds randomness to these hashes via salt values generated with the strongest entropy generators available on the platform (see [api:RandomGenerator]). This prevents brute force attacks with [Rainbow tables](http://en.wikipedia.org/wiki/Rainbow_table). Strong passwords are a crucial part of any system security. So in addition to storing the password in a secure fashion, you can also enforce specific password policies by configuring a [api:PasswordValidator]: :::php $validator = new PasswordValidator(); $validator->minLength(7); $validator->checkHistoricalPasswords(6); $validator->characterStrength('lowercase','uppercase','digits','punctuation'); Member::set_password_validator($validator); In addition, you can tighten password security with the following configuration settings: * `Member.password_expiry_days`: Set the number of days that a password should be valid for. * `Member.lock_out_after_incorrect_logins`: Number of incorrect logins after which the user is blocked from further attempts for the timespan defined in `$lock_out_delay_mins` * `Member.lock_out_delay_mins`: Minutes of enforced lockout after incorrect password attempts. Only applies if `lock_out_after_incorrect_logins` is greater than 0. ## Related * [http://silverstripe.org/security-releases/](http://silverstripe.org/security-releases/) * [Best-practices for securing MySQL (securityfocus.com)](http://www.securityfocus.com/infocus/1726)