pass01

查看源码，为js前端限制，在开发者工具中关闭js然后上传木马连接即可

function checkFile() {
    var file = document.getElementsByName('upload_file')[0].value;
    if (file == null || file == "") {
        alert("请选择要上传的文件!");
        return false;
    }
    //定义允许上传的文件类型
    var allow_ext = ".jpg|.png|.gif";
    //提取上传文件的类型
    var ext_name = file.substring(file.lastIndexOf("."));
    //判断上传文件类型是否允许上传
    if (allow_ext.indexOf(ext_name + "|") == -1) {
        var errMsg = "该文件不允许上传，请上传" + allow_ext + "类型的文件,当前文件类型为：" + ext_name;
        alert(errMsg);
        return false;
    }
}

pass02

查看源码发现是PHP源码，审计之后发现是MIME检测:

($_FILES['upload_file']['type'] == 'image/jpeg') || ($_FILES['upload_file']['type'] == 'image/png') || ($_FILES['upload_file']['type'] == 'image/gif')

源码：

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
    if (file_exists(UPLOAD_PATH)) {
        if (($_FILES['upload_file']['type'] == 'image/jpeg') || ($_FILES['upload_file']['type'] == 'image/png') || ($_FILES['upload_file']['type'] == 'image/gif')) {
            $temp_file = $_FILES['upload_file']['tmp_name'];
            $img_path = UPLOAD_PATH . '/' . $_FILES['upload_file']['name']            
            if (move_uploaded_file($temp_file, $img_path)) {
                $is_upload = true;
            } else {
                $msg = '上传出错！';
            }
        } else {
            $msg = '文件类型不正确，请重新上传！';
        }
    } else {
        $msg = UPLOAD_PATH.'文件夹不存在,请手工创建！';
    }
}

使用burp suite进行抓包,修改content-type字段绕过MIMIE检测即可

pass03

查看PHP源码，进行审计，发现可以进行黑名单绕过。

绕过姿势有：php5, php4, php3, phtml

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
    if (file_exists(UPLOAD_PATH)) {
        $deny_ext = array('.asp','.aspx','.php','.jsp');
        $file_name = trim($_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
        $file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA
        $file_ext = trim($file_ext); //收尾去空

        if(!in_array($file_ext, $deny_ext)) {
            $temp_file = $_FILES['upload_file']['tmp_name'];
            $img_path = UPLOAD_PATH.'/'.date("YmdHis").rand(1000,9999).$file_ext;            
            if (move_uploaded_file($temp_file,$img_path)) {
                 $is_upload = true;
            } else {
                $msg = '上传出错！';
            }
        } else {
            $msg = '不允许上传.asp,.aspx,.php,.jsp后缀文件！';
        }
    } else {
        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';
    }
}

pass04

使用.htaccess文件创建局部配置作用域，使得上传的文件可被PHP解析

0x01.源码

放个源码：

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
    if (file_exists(UPLOAD_PATH)) {
        $deny_ext = 
        array(".php",".php5",".php4",".php3",".php2",".php1",".html",".htm",".phtml",".pht",".pHp",
        ".pHp5",".pHp4",".pHp3",".pHp2",".pHp1",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".j
        sw",".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",".ini");
        $file_name = trim($_FILES['upload_file']['name']);
        $file_name = deldot($file_name);//删除文件名末尾的点
        $file_ext = strrchr($file_name, '.');//截取碰到的第一个'.'后的内容
        $file_ext = strtolower($file_ext); //转换为小写
        $file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA
        $file_ext = trim($file_ext); //收尾去空

        if (!in_array($file_ext, $deny_ext)) {
            $temp_file = $_FILES['upload_file']['tmp_name'];
            $img_path = UPLOAD_PATH.'/'.$file_name;
            if (move_uploaded_file($temp_file, $img_path)) {
                $is_upload = true;
            } else {
                $msg = '上传出错！';
            }
        } else {
            $msg = '此文件不允许上传!';
        }
    } else {
        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';
    }
}

发现黑名单中没有.htaccess，考虑上传.htaccess文件创造局部的目录作用域

0x02..htaccess介绍

.htaccess 文件是Apache中有一种特殊的文件，其提供了针对目录改变配置的方法，即在一个特定的文档目录中放置一个包含一条或多条指令的文件，以作用于此目录及其所有子目录。管理员可以通过 Apache 的 AllowOverride 指令来设置。

基本的攻击语法:

Sethandler

AddType





<ifModule mime_module>
AddHandler php5-script .jpg           <!-- 将.jpg文件按照php代码进行解析执行 -->
AddType application/x-httpd-php .jpg  <!-- 将.jpg文件按照php代码进行解析执行 -->

Sethandler application/x-httpd-php    <!-- 将该目录及子目录下的文件均按照php文件解析执行 -->

</ifModule>                           <!-- 该种匹配方式并不推荐，极易造成误伤 -->


<FilesMatch "muma.jpg">

Sethandler application/x-httpd-php    <!-- 将匹配到的 muma.jpg 文件按照php解析执行 -->

Addhandler php5-script .jpg           <!-- 将匹配到的 muma.jpg 文件按照php解析执行 -->

</FilesMatch>                         <!-- 该种匹配方式较为精准，不会造成大批的误伤情况 -->

0x03..htaccess文章链接:

cloud.tencent.com/developer/a…

pass05

源码：

pass06

发现没有了strtolower()函数，考虑使用大小写绕过姿势

pass07

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