奇安信攻防社区-Wordpress敏感信息泄漏漏洞 CVE-2021-38314 代码审计

Wordpress敏感信息泄漏漏洞 CVE-2021-38314 代码审计

WordPress Redux Framework class-redux-helpers.php 敏感信息泄漏漏洞 CVE-2021-38314 | 代码审计复现

WordPress Redux Framework class-redux-helpers.php 敏感信息泄漏漏洞 CVE-2021-38314 | 代码审计复现
==================================================================================

漏洞描述
----

2021年8月爆出Redux Framework存在未授权的敏感信息泄露漏洞，CVE编号为CVE-2021-38314，影响v4.2.11及以下版本，发送特定的请求包可以在未授权的情况下获取服务器敏感信息

漏洞影响
----

Redux Framework &lt;= v4.2.11

插件名
---

Redux Framework  
<https://github.com/reduxframework/redux-framework>

漏洞复现
----

影响范围为 v4.211 以下, 看一下版本间的更新差异  
[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-c0e83cbfcacce79ae68a52f280eda9091565682f.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-c0e83cbfcacce79ae68a52f280eda9091565682f.png)

这里将 add\_action 注册的函数都删除掉了，本地安装查看函数相关代码  
[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-2b6df32d2b1ee4b9836fdd55209af6718db2aa9b.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-2b6df32d2b1ee4b9836fdd55209af6718db2aa9b.png)

```php
$support_hash = md5( md5( Redux_Functions_Ex::hash_key() . '-redux' ) . '-support' );
add_action( 'wp_ajax_nopriv_' . $support_hash, array( 'Redux_Helpers', 'support_args' ) );
add_action( 'wp_ajax_' . $support_hash, array( 'Redux_Helpers', 'support_args' ) );
$hash_arg = md5( trailingslashit( network_site_url() ) . '-redux' );
add_action( 'wp_ajax_nopriv_' . $hash_arg, array( 'Redux_Helpers', 'hash_arg' ) );
add_action( 'wp_ajax_' . $hash_arg, array( 'Redux_Helpers', 'hash_arg' ) );
add_action( 'wp_ajax_redux_support_hash', array( 'Redux_Functions', 'support_hash' ) );

add_filter( 'redux/tracking/options', array( 'Redux_Helpers', 'redux_stats_additions' ) );
```

查看 add\_action 注册的函数 hash\_arg() 和 support\_args()

```php
public static function hash_arg() {
            echo esc_html( md5( Redux_Functions_Ex::hash_key() . '-redux' ) );
            die();
        }
```

```php
public static function support_args() {
            header( 'Expires: Mon, 26 Jul 1997 05:00:00 GMT' );
            header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . 'GMT' );
            header( 'Expires: Sat, 26 Jul 1997 05:00:00 GMT' );
            header( 'Cache-Control: no-store, no-cache, must-revalidate' );
            header( 'Cache-Control: post-check=0, pre-check=0', false );
            header( 'Pragma: no-cache' );

$instances = Redux::all_instances();

if ( isset( $_REQUEST['i'] ) && ! empty( $_REQUEST['i'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification
                if ( is_array( $instances ) && ! empty( $instances ) ) {
                    foreach ( $instances as $opt_name => $data ) {
                        if ( md5( $opt_name . '-debug' ) === $_REQUEST['i'] ) { // phpcs:ignore WordPress.Security.NonceVerification
                            $array = $data;
                        }
                    }
                }

if ( isset( $array ) ) {

// We only want the extension names and versions.
                    $array->extensions = self::get_extensions( $opt_name );
                    $to_return         = array();

// Filter out all the unwanted data.
                    foreach ( $array as $key => $value ) {
                        if ( in_array(
                            $key,
                            array(
                                // 'fields',
                                'extensions',
                                'sections',
                                'args',
                                // 'field_types'
                            ),
                            true
                        ) ) {
                            $to_return[ $key ] = $value;
                        } else { // phpcs:ignore Generic.CodeAnalysis.EmptyStatement
                            // phpcs:ignore Squiz.PHP.CommentedOutCode
                            /* echo $key.PHP_EOL; */
                        }
                    }
                    $array = $to_return;
                } else {
                    die();
                }
            } else {
                $array = self::get_statistics_object();
                if ( is_array( $instances ) && ! empty( $instances ) ) {
                    $array['instances'] = array();
                    foreach ( $instances as $opt_name => $data ) {
                        $array['instances'][] = $opt_name;
                    }
                }
                $array['key'] = md5( Redux_Functions_Ex::hash_key() );
            }

ksort( $array ); // Let's make that pretty.

// phpcs:ignored WordPress.PHP.NoSilencedErrors, WordPress.Security.EscapeOutput
            echo @htmlspecialchars( @wp_json_encode( $array, true ), ENT_QUOTES );

die();
        }
```

support\_args() 函数 $\_REQUEST\['i'\] 为空，来到另一处分支

```php
} else {
                $array = self::get_statistics_object();
                if ( is_array( $instances ) && ! empty( $instances ) ) {
                    $array['instances'] = array();
                    foreach ( $instances as $opt_name => $data ) {
                        $array['instances'][] = $opt_name;
                    }
                }
                $array['key'] = md5( Redux_Functions_Ex::hash_key() );
            }
```

跟踪 get\_statistics\_object() 函数，该函数可以获取 插件等环境变量 信息  
[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-b82a54be4a24c84dc982ff13b8c3d13991425d46.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-b82a54be4a24c84dc982ff13b8c3d13991425d46.png)

回过头可以看到该函数 为 wp\_ajax*nopriv*\* 可未授权调用  
[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-b32945e773400971efaae18f8fc0c8f7afaaa023.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-b32945e773400971efaae18f8fc0c8f7afaaa023.png)

其中需要变量 $support\_hash, 跟踪 hash\_key() 方法

```php
$support_hash = md5( md5( Redux_Functions_Ex::hash_key() . '-redux' ) . '-support' );
```

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-358db193767b7fd663a0b09caa9f5589d6fb8bc6.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-358db193767b7fd663a0b09caa9f5589d6fb8bc6.png)

wp-config.php 中存在 AUTH\_KEY 参数，为随机值  
[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-caf89777a57c971be3b8fd15dcc76288821a1c57.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-caf89777a57c971be3b8fd15dcc76288821a1c57.png)

这里回到 hash\_arg() 函数[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-cc42f4b8bca2b56e4af44e80377ca241224da233.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-cc42f4b8bca2b56e4af44e80377ca241224da233.png)

```php
public static function hash_arg() {
            echo esc_html( md5( Redux_Functions_Ex::hash_key() . '-redux' ) );
            die();
        }
```

这里就调用到了 Redux\_Functions\_Ex::hash\_key() 中的函数，且返回 md5值  
回到刚刚的代码中，可以发现得到的结果同样也是 $support\_hash 我们所需要知道的参数，下面为等价替换

```php
$support_hash = md5(hash_arg(). '-support' );
```

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-7b1f94c101500a779ce57a9761a0106fbdc95e52.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-7b1f94c101500a779ce57a9761a0106fbdc95e52.png)

这样我们就获取到了一个利用链

```php
$hash_arg = md5( trailingslashit( network_site_url() ) . '-redux' );
add_action( 'wp_ajax_nopriv_' . $hash_arg, array( 'Redux_Helpers', 'hash_arg' ) );
|
获取 md5( Redux_Functions_Ex::hash_key() . '-redux') 值
|
$support_hash = md5( md5( Redux_Functions_Ex::hash_key() . '-redux' ) . '-support' );
add_action( 'wp_ajax_nopriv_' . $support_hash, array( 'Redux_Helpers', 'support_args' ) );
|
调用函数 support_args 获取系统敏感信息
```

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-39d9c5d623a42ab0d5b3897a4fd2d78e285d48c7.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-39d9c5d623a42ab0d5b3897a4fd2d78e285d48c7.png)

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-1abb7eaa3e3a808eaf7f3a0e0f63950c9186b216.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-1abb7eaa3e3a808eaf7f3a0e0f63950c9186b216.png)

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-bb4c083fd1c2b3252a43d20f993e77ab96d0ebb7.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-bb4c083fd1c2b3252a43d20f993e77ab96d0ebb7.png)

[![](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-e1f0264bb7c0db89a628bfb70b79fcb49784e67d.png)](https://shs3.b.qianxin.com/attack_forum/2021/12/attach-e1f0264bb7c0db89a628bfb70b79fcb49784e67d.png)

成功获取到了插件版本等有关信息

发表于 2021-12-03 09:51:54
阅读 ( 7047 )
分类：代码审计

Wordpress敏感信息泄漏漏洞 CVE-2021-38314 代码审计

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