文件上传漏洞基础/::$DATA绕过上传/叠加特征绕过/双写绕过

一、NTFS交换数据流::$DATA绕过上传

如果后缀名没有对::$DATA进行判断，利用windows系统NTFS特征可以绕过上传

在window的时候如果文件名+"::$DATA"会把::$DATA之后的数据当成文件流处理,不会检测后缀名，且保持::$DATA之前的文件名，其实和空格绕过点绕过类似

upload-pass08

代码分析

 $deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess");
        $file_name = trim($_FILES['upload_file']['name']);
        $file_name = deldot($file_name);//删除文件名末尾的点
        $file_ext = strrchr($file_name, '.');
        $file_ext = strtolower($file_ext); //转换为小写
        $file_ext = trim($file_ext); //首尾去空

看到这里还是黑名单过滤，比前面少了一行

 $file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA

尝试上传

我们开启抓包，上传test.php 抓包中修改 test.php::$DATA

上传成功

二、利用windows环境的叠加特征绕过上传

在windows中如果上传文件test.php:.jpg时，会在目录下产生空白的文件test.php

再利用php和windows环境的叠加属性

正则匹配：

双引号等同于点

大于号等同于问号（任意一个字符）

小于号等同于星号（任意个任意字符）

upload-pass09

代码分析

其实就是把前面的代码加上了，基本上算后缀名检测的防护都开了，这种情况下我们可以尝试使用叠加特征上传

尝试上传

先上传一个test.php 抓包中加入:.jpg

可以看到，我们上传进了一个test.php但是是0kb，也就是没有任何内容的空文件

下一步就是写入这个文件，我们再次上传抓包

仔细看这个数据包，向test.php中写入<?php phpinfo();?>其实这里有写入的过程，我们只需要把test.php写成我们刚才传入文件的名字并且绕过后缀,使用正则匹配

将test.php变成 test.>>>

写入成功，上传成功

三、双写绕过

这个就很简单了

upload-pass10

代码分析

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
    if (file_exists($UPLOAD_ADDR)) {
        $deny_ext = array("php","php5","php4","php3","php2","html","htm","phtml","jsp","jspa","jspx","jsw","jsv","jspf","jtml","asp","aspx","asa","asax","ascx","ashx","asmx","cer","swf","htaccess");

        $file_name = trim($_FILES['upload_file']['name']);
        $file_name = str_ireplace($deny_ext,"", $file_name);
        if (move_uploaded_file($_FILES['upload_file']['tmp_name'], $UPLOAD_ADDR . '/' . $file_name)) {
            $img_path = $UPLOAD_ADDR . '/' .$file_name;
            $is_upload = true;
        }
    } else {
        $msg = $UPLOAD_ADDR . '文件夹不存在,请手工创建！';
    }
}

str_ireplace("黑名单","空",后缀名)

从后缀名中匹配黑名单中的字符串，如果出现则换成空，从左到右匹配

类似sql注入中的双写绕过

如.pphphp,从左往右匹配到第一个php时去掉变为.php，达到了绕过的目的

尝试上传

上传成功