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CSZ CMS 1.2.7 xss分析与复现

2020-05-18 13:11

CSZ CMS 1.2.7 xss分析与复现

简介

CSZ CMS是一个开源Web应用程序,允许管理网站上的所有内容和设置。CSZ CMS是在Codeigniter3的基础上构建的,并设计了Bootstrap3的结构,这应该使您的网站轻松响应。

CSZ CMS基于服务器端脚本语言PHP,并使用MySQL或MariaDB数据库进行数据存储。CSZ CMS是开源的内容管理系统。

漏洞概述

拥有访问私有消息的未授权用户可以向管理面板嵌入Javascript代码。

影响版本

1.2.7

环境搭建

下载地址:https://sourceforge.net/projects/cszcms/files/install/CSZCMS-V1.2.7.zip/download

按照指示安装即可

漏洞复现

新建一个用户

点击inbox发送私信,选定管理员用户


修改User-Agent为<script>alert(1)</script>

管理员登陆后台即触发xss

分析

查看数据库中的email_logs可知,将访问的user-agent存储到了数据库中

我们首先观察路由,漏洞点在/member/insertpm页面,查看控制器,找到cszcms/controllers/Member.php


找到insertpm方法:


关注点在下半部分:

$this->input->post即是调用的system/core/Input.php的post方法:


当$xss_clean的参数设置为true,则会进行xss过滤,这也是为什么发送信息处并没有出现xss

继续看,$this->Csz_auth_model->send_pm方法位于cszcms/models/Csz_auth_model.php中的send_pm():

/**
* Send multiple Private Messages
* Send multiple private messages to another users
*
* @param array $receiver_ids Array of User ids of private message receiver
* @param string $title Title/subject
* @param string $message Message
* @param int $sender_id User id of private message sender
* @param string $re_message Reply the original message
*
* @return array/bool Array with User ID's as key and TRUE or a specific error message OR FALSE if sender doesn't exist
*/
public function send_pm($receiver_ids, $title, $message, $sender_id = '', $re_message = '') {
if (!$sender_id) {
$sender_id = $this->session->userdata('user_admin_id');
}
if ($sender_id && (!$this->is_useractive($sender_id))) {
return FALSE;
}else{
if ($receiver_ids && is_numeric($receiver_ids) && $sender_id != $receiver_ids) {
if($re_message){
$message = '{[' . str_replace("\r\n" . "\r\n", "\r\n", $re_message) . "]} " . "\r\n" . "\r\n" . $message;
}
$data = array(
'sender_id' => $sender_id,
'receiver_id' => $receiver_ids,
'title' => $title,
'message' => $message,
'date_sent' => date('Y-m-d H:i:s')
);
$this->db->insert('user_pms', $data);
$sender_user = $this->Csz_admin_model->getUser($sender_id);
$receive_user = $this->Csz_admin_model->getUser($receiver_ids);
if($receive_user->pm_sendmail == '1'){
$config = $this->Csz_model->load_config();
$message_html = 'Dear ' . $receive_user->name . ',<br><br>' . $message . '<br><br>Best Regards,<br>'.$sender_user->name;
@$this->Csz_model->sendEmail($receive_user->email, '[PM] ' . $title . ' ('.$config->site_name.')', $message_html, $sender_user->email, $sender_user->name);
}
return TRUE;
}else{
return FALSE;
}
}
}

调用了@$this->Csz_model->sendEmail方法,位于cszcms/models/Csz_model.php,我们继续跟进:

public function sendEmail($to_email, $subject, $message, $from_email, $from_name = '', $bcc = '', $reply_to = '', $alt_message = '', $attach_file = array(), $save_log = TRUE) {
$this->load->library('email');
$load_conf = $this->load_config();
$protocal = $load_conf->email_protocal;
if (!$protocal) {
$protocal = 'mail';
}
$config = array();
$config['useragent'] = $this->Csz_admin_model->cszGenerateMeta();
$config['protocol'] = $protocal; /* mail, sendmail, smtp */
if ($protocal == 'smtp') {
$config['smtp_host'] = $load_conf->smtp_host;
$config['smtp_user'] = $load_conf->smtp_user;
$config['smtp_pass'] = $load_conf->smtp_pass;
$config['smtp_port'] = $load_conf->smtp_port;
} else if ($protocal == 'sendmail' && $load_conf->sendmail_path) {
$config['mailpath'] = $load_conf->sendmail_path;
}
$config['mailtype'] = 'html';
$config['charset'] = 'utf-8';
$config['wordwrap'] = TRUE;
$this->email->initialize($config);
$this->email->set_newline("\r\n");
$this->email->from($from_email, $from_name); // change it to yours
$this->email->to($to_email); // change it to yours
$this->email->subject($subject);
$this->email->message($message);
if ($bcc) {
$this->email->bcc($bcc);
}
if($reply_to){
$this->email->reply_to($reply_to);
}
if ($alt_message) {
$this->email->set_alt_message($alt_message);
}
if (is_array($attach_file) && !empty($attach_file)) {
foreach ($attach_file as $value) {
$this->email->attach($value, 'attachment');
}
}
if ($this->email->send()) {
$result = 'success';
} else {
$result = $this->email->print_debugger(FALSE);
}
if($save_log === TRUE && $load_conf->email_logs == 1){
$data = array(
'to_email' => $to_email,
'from_email' => $from_email,
'from_name' => $from_name,
'subject' => $subject,
'message' => $message,
'email_result' => $result,
);
$this->db->set('user_agent', $this->input->user_agent(), TRUE);
$this->db->set('ip_address', $this->input->ip_address(), TRUE);
$this->db->set('timestamp_create', $this->timeNow(), TRUE);
$this->db->insert('email_logs', $data);
$this->db->cache_delete_all();
unset($data);
}
unset($to_email, $subject, $message, $from_email, $from_name, $bcc, $reply_to, $alt_message, $attach_file, $save_log, $config, $load_conf, $protocal);
return $result;
}

关键就在于后面的数据库操作:

$this->db->set('user_agent', $this->input->user_agent(), TRUE);
$this->db->set('ip_address', $this->input->ip_address(), TRUE);
$this->db->set('timestamp_create', $this->timeNow(), TRUE);
$this->db->insert('email_logs', $data);
$this->db->cache_delete_all();

$this->db->set方法位于:system/database/DB_query_builder.php:

/**
* The "set" function.
*
* Allows key/value pairs to be set for inserting or updating
*
* @param mixed
* @param string
* @param bool
* @return CI_DB_query_builder
*/
public function set($key, $value = '', $escape = NULL)
{
$key = $this->_object_to_array($key);

if ( ! is_array($key))
{
$key = array($key => $value);
}

is_bool($escape) OR $escape = $this->_protect_identifiers;

foreach ($key as $k => $v)
{
$this->qb_set[$this->protect_identifiers($k, FALSE, $escape)] = ($escape)
? $this->escape($v) : $v;
}

return $this;
}

简单理解即为插入或更新值作初始化

继续,$this->input->user_agent()位于:system/core/Input.php,其具体实现如下:

/**
* Fetch User Agent string
*
* @return string|null User Agent string or NULL if it doesn't exist
*/
public function user_agent($xss_clean = NULL)
{
return $this->_fetch_from_array($_SERVER, 'HTTP_USER_AGENT', $xss_clean);
}

这里的xss过滤操作默认是null,也就是没有过滤

这就是问题所在,我们即可以通过篡改user_agent的值实现xss,往下看,$this->db->insert('email_logs', $data)即向emali_logs表插入数据,$this->db->insert实现如下(system/core/Input.php):

/**
* Insert
*
* Compiles an insert string and runs the query
*
* @param string the table to insert data into
* @param array an associative array of insert values
* @param bool $escape Whether to escape values and identifiers
* @return bool TRUE on success, FALSE on failure
*/
public function insert($table = '', $set = NULL, $escape = NULL)
{
if ($set !== NULL)
{
$this->set($set, '', $escape);
}

if ($this->_validate_insert($table) === FALSE)
{
return FALSE;
}

$sql = $this->_insert(
$this->protect_identifiers(
$this->qb_from[0], TRUE, $escape, FALSE
),
array_keys($this->qb_set),
array_values($this->qb_set)
);

$this->_reset_write();
return $this->query($sql);
}

依然没有任何过滤

然而,关于为什么登入后台即会弹窗,搜索一番后发现,开发者直接将其echo出来(cszcms/views/admin/home.php):

修复

在1.2.8中删除了相关代码(cszcms/views/admin/home.php):

参考链接:

CI框架相关:https://www.cnblogs.com/lazycat-cz/p/4315453.html

cszcms开发文档:https://docs.cszcms.com/


知识来源: xz.aliyun.com/t/7730

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