风炫安全web安全学习第三十七节课 15种上传漏洞讲解(二)

05后缀名黑名单校验之上传.htaccess绕过

还是使用黑名单，禁止上传所有web容器能解析的脚本文件的后缀

$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",".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");

        $file_name = trim($_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 = '此文件不允许上传!';

        }

    } else {

        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

上传.htaccess 静态规则让web容器把任意文件解析成PHP脚本文件

<FilesMatch "fx">

SetHandler application/x-httpd-php

</FilesMatch>

演示地址：Pass-04/index.php

06后缀名黑名单校验之利用大小写绕过

还是黑名单，但是这次把.htaccess也限制了

$is_upload = false;

$msg = null;

if (isset($_POST['submit'])) {

    if (file_exists(UPLOAD_PATH)) {

        $deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".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, '.');

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

        $file_ext = trim($file_ext); //首尾去空

        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 = '此文件类型不允许上传！';

        }

    } else {

        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

在burp里改包，把文件名改成.phP 利用大小写绕过检测

演示地址：Pass-05/index.php

07后缀名黑名单校验之burp改包文件名后加空格绕过

还是黑名单，此时已经把所有后缀名改为小写，进行验证。

$is_upload = false;

$msg = null;

if (isset($_POST['submit'])) {

    if (file_exists(UPLOAD_PATH)) {

        $deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".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 = $_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

        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 = '此文件不允许上传';

        }

    } else {

        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

在burp里改包，把文件名改成.php 在后缀名处加空格(%00) 绕过

此种绕过方式受系统环境和Web容器影响

演示地址：Pass-06/index.php

08后缀名黑名单校验之burp改包文件后缀加“.”绕过

还是黑名单，修复了上面的漏洞把文件后缀首尾空格去掉，进行验证。

$is_upload = false;

$msg = null;

if (isset($_POST['submit'])) {

    if (file_exists(UPLOAD_PATH)) {

        $deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".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']);

        $file_ext = strrchr($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); //首尾去空

        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 = '此文件类型不允许上传！';

        }

    } else {

        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

在burp里改包，把文件名改成.php. 在后缀名处加空格.绕过

但是没有对后缀名进行去”.”处理，利用windows特性，会自动去掉后缀名中最后的”.”，可在后缀名中加”.”绕过：

演示地址：Pass-07/index.php

09后缀名黑名单校验之利用windows特性::$DATA绕过

还是黑名单策略，修复了上面的漏洞，也去掉了后缀名中的的点“.”

$is_upload = false;

$msg = null;

if (isset($_POST['submit'])) {

    if (file_exists(UPLOAD_PATH)) {

        $deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".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

        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 = '此文件类型不允许上传！';

        }

    } else {

        $msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

在burp里改包，把文件名改成.php::$DATA 在后缀名处加::$DATA绕过

这道题利用的是Windows下NTFS文件系统的一个特性，即NTFS文件系统的存储数据流的一个属性 DATA 时，就是请求 a.asp 本身的数据，如果a.asp 还包含了其他的数据流，比如 a.asp:lake2.asp，请求 a.asp:lake2.asp::$DATA，则是请求a.asp中的流数据lake2.asp的流数据内容。

演示地址：Pass-08/index.php

10后缀名黑名单校验之双写文件名绕过

这里是用替换的方式替换了后缀名。

$is_upload = false;

$msg = null;

if (isset($_POST['submit'])) {

    if (file_exists(UPLOAD_PATH)) {

        $deny_ext = array("php","php5","php4","php3","php2","html","htm","phtml","pht","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);// preg_match_all

        $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 = UPLOAD_PATH . '文件夹不存在,请手工创建！';

    }

}

绕过方式

在burp里改包，把文件名改成双写，比如.php 改成 .phphpp 把其中一个php替换掉之后组成一个新的php文件

演示地址：Pass-10/index.php

11后缀名白名单校验之%00截断

可以看到是白名单，只能'jpg','png','gif'格式的文件访问，保存的路径是get传递的

$is_upload = false;

$msg = null;

if(isset($_POST['submit'])){

    $ext_arr = array('jpg','png','gif');

    $file_ext = substr($_FILES['upload_file']['name'],strrpos($_FILES['upload_file']['name'],".")+1);

    if(in_array($file_ext,$ext_arr)){

        $temp_file = $_FILES['upload_file']['tmp_name'];

        $img_path = $_GET['save_path']."/".rand(10, 99).date("YmdHis").".".$file_ext;

        if(move_uploaded_file($temp_file,$img_path)){

            $is_upload = true;

        } else {

            $msg = '上传出错！';

        }

    } else{

        $msg = "只允许上传.jpg|.png|.gif类型文件！";

    }

}

绕过方式

在burp里改包，使用在url参数上%00截断绕过

演示地址：Pass-11/index.php

12后缀名白名单校验之00截断

白名单，只能'jpg','png','gif'格式的文件访问，不过保存的路径是post传递的

$is_upload = false;

$msg = null;

if(isset($_POST['submit'])){

    $ext_arr = array('jpg','png','gif');

    $file_ext = substr($_FILES['upload_file']['name'],strrpos($_FILES['upload_file']['name'],".")+1);

    if(in_array($file_ext,$ext_arr)){

        $temp_file = $_FILES['upload_file']['tmp_name'];

        $img_path = $_POST['save_path']."/".rand(10, 99).date("YmdHis").".".$file_ext;

        if(move_uploaded_file($temp_file,$img_path)){

            $is_upload = true;

        } else {

            $msg = "上传失败";

        }

    } else {

        $msg = "只允许上传.jpg|.png|.gif类型文件！";

    }

}

绕过方式

在burp里改包，在post包里用00截断绕过，这里只能改包的hex值，手动改%00字符串无效

演示地址：Pass-12/index.php

13图片文件格式验证之图片木马

这里是读取了文件的内容，以文件的内容来判断是否是图片。

function getReailFileType($filename){

    $file = fopen($filename, "rb");

    $bin = fread($file, 2); //只读2字节

    fclose($file);

    $strInfo = @unpack("C2chars", $bin);

    $typeCode = intval($strInfo['chars1'].$strInfo['chars2']);

    $fileType = '';

    switch($typeCode){

        case 255216:

            $fileType = 'jpg';

            break;

        case 13780:

            $fileType = 'png';

            break;

        case 7173:

            $fileType = 'gif';

            break;

        default:

            $fileType = 'unknown';

        }

        return $fileType;

}

$is_upload = false;

$msg = null;

if(isset($_POST['submit'])){

    $temp_file = $_FILES['upload_file']['tmp_name'];

    $file_type = getReailFileType($temp_file);

    if($file_type == 'unknown'){

        $msg = "文件未知，上传失败！";

    }else{

        $img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").".".$file_type;

        if(move_uploaded_file($temp_file,$img_path)){

            $is_upload = true;

        } else {

            $msg = "上传出错！";

        }

    }

}

绕过方式

制作图片一句话木马上传 copy a.jpg/b + a.txt = a1.jpg

演示地址：Pass-13/index.php

14 条件竞争上传

这里是现把上传文件移动到目标文件夹，后对文件名进行判断。不符合条件的都删除掉。

$is_upload = false;

$msg = null;

if(isset($_POST['submit'])){

    $ext_arr = array('jpg','png','gif');

    $file_name = $_FILES['upload_file']['name'];

    $temp_file = $_FILES['upload_file']['tmp_name'];

    $file_ext = substr($file_name,strrpos($file_name,".")+1);

    $upload_file = UPLOAD_PATH . '/' . $file_name;

    if(move_uploaded_file($temp_file, $upload_file)){

        if(in_array($file_ext,$ext_arr)){

             $img_path = UPLOAD_PATH . '/'. rand(10, 99).date("YmdHis").".".$file_ext;

             rename($upload_file, $img_path);

             $is_upload = true;

        }else{

            $msg = "只允许上传.jpg|.png|.gif类型文件！";

            unlink($upload_file);

        }

    }else{

        $msg = '上传出错！';

    }

}

绕过方式

只要利用竞争上传，上传的php文件内容为写入shell文件，然后不断的访问该文件，只要访问成功，便可以写入shell，直接利用burp的intruder模块上传文件，同时不停的访问这个文件。

参考：

http://blog.evalshell.com/2020/12/20/风炫安全web安全学习第三十七节课-15种上传漏洞讲解/

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