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文件上传漏洞靶场分析 UPLOAD
Web前端之巅
2022-08-16 21:30:45 2022-08-16
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文件上传漏洞靶场(作者前言)

项目地址:https://github.com/c0ny1/upload-labs

文件上传漏洞

产生原理

PASS 1)

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;
}
}

源码分析

这是一串JS前端语言编写的文件上传 这边限制上传的文件类型为JPG;PNG;GIF三种 通过file.substring(file.lastIndexof(".")); #获取文件后缀名 并判断文件的后缀名是否等于允许的文件类型 没有对文件名后缀做过滤限制

绕过方法

*JS是前端开发语言 1.更改php文件后缀名,上传图片文件时可以通过Burpsuite 进行拦截请求数据包并更改文件后缀名 2.F12查看前端代码 并复制 程序执行的过滤,按需求对其进行删改操作 3.修改form表单 定义action 进行直接上传的操作

防御方法

验证文件真实性 过滤空格、点、大小写、双写、流文件

PASS 2)

$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!';
}
}

源码分析

if

(($_FILES['upload_file']['type'] == 'image/jpeg') ||
($_FILES['upload_file']['type'] == 'image/png') ||
($_FILES['upload_file']['type'] == 'image/gif'))
这边仅对上传的文件类型做了过滤 没有对上传的文件后缀做过滤 且请求方式为POST

绕过方法

  1. 上传php文件时使用Burpsuite 更改请求头中的内容类型(content-type:image/jpeg:png:gif) 任意一种允许的文件类型。
  2. 上传转格式的包含php执行程序的图片文件,使用Burpsuite 更改后缀名

防御方法

1.验证图片文件的真实性

2.过滤上传文件的后缀名

PASS 3)

$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!';
}
}

源码分析

$deny_ext = array('.asp','.aspx','.php','.jsp');

这边使用黑名单防御方法 不允许 后缀为.asp ; .aspx ; .php ; .jsp 的后端语言文件
if(!in_array($file_ext, $deny_ext))
取出用户后缀名,如果不存在限制的后缀名 则执行接下来的操作

绕过方法

  1. 使用php文件时 可以使用其他的php语言支持的后缀名 比如php3 phtml

通过查阅apache配置文件 httpd.conf中的 AddType application/x-httpd-php .php .php3 .phtml

这是phpstudy(PHP 5.2.17) apache配置文件中默认配置支持的文件.php .php3 .phtml

application/x-httpd-php :指定应用程序php的可用后缀名

原理:Addtype 添加类型 可以手动指定任意后缀名让apache服务解析至PHP文件 认定位php程序并执行
···比如: AddType application/x-httpd-php .abc 这里以.abc为后缀的文件将被认为是php执行文件

  1. 使用.htaccess 分布式配置文件 将上传目录的中的所有文件的执行策略更改为php执行程序

防御方法

  1. 过滤完整的后端执行后缀名
  2. 过滤分布式配置文件.htaccess
  3. 使用白名单防御方法(只允许)

PASS 4)

$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!';
}
}

源码分析

$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");
以上源码 没有对.htaccess配置文件进行限制

$file_name = trim($_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
以上源码 trim函数使用两次

绕过方法

  1. 上传.htaccess 分布式配置文件 修改文件执行策略 针对目录改变配置的方法
    SetHandle application/x-httpd-php
    告诉apache 当前目录下的所有后缀名解析为php

<FilesMatch "file_name.png">

SetHandler application/x-httpd-php
告诉apache,只对当前目录下 file_name.png 文件当作php代码执行,其他文件照常不变

  1. 上传文件时使用BP拦截请求消息包 更改后缀名为.php. .绕过

程序执行时从上至下执行首先对文件名进行首尾清除空格

接着删除文件末尾的.
最后删除文件末尾的空格

即file.php. . 上传时

执行deldot($file_name)>
file.php.$nbsp 上传中执行trim($file_ext)>
留下file.php.

防御方法

  1. 过滤htaccess 限制上传此文件
  2. 使用白名单防御方法 只允许想要上传的格式(白名单和黑名单防御方法根据需求定)

PASS 5)

$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!';
}
}

源码分析

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
以上源码 trim函数使用两次,且没有对后缀名的大小写进行过滤 —— strtolower() 将字符转为小写

绕过方法

  1. 利用win系统的特性因为大小写不敏感 可以使用大小写绕过的方法绕过 即.PHp 这一特性不适用Linux系统
  2. 双写后缀名格式

    上传文件时使用BP拦截请求消息包 更改后缀名为.php. .绕过 即file.php. . 上传时 执行deldot($file_name)> file.php.$nbsp 上传中执行trim($file_ext)> 留下file.php.

防御方法

  1. 白名单防御方法 只允许上传图片格式的文件(白名单和黑名单防御方法根据需求定)
  2. 限制大小写 转换为小写

PASS 6)

$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!';
}
}

源码分析

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

这里没有使用trim() 清除字符首尾空格函数 可以利用系统特性后缀名末尾为空格即为空这一文件

绕过方法

  1. 使用BP拦截请求消息 更改后缀名+空格 即.php+%20

防御方法

  1. 白名单防御法 只允许想要上传进入的文件格式
  2. 使用trim函数

PASS 7)

$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!';
}
}

源码分析

$file_name = trim($_FILES['upload_file']['name']);

$file_ext = trim($file_ext); //首尾去空
# trim() 函数移除字符串两侧的空白字符或其他预定义字符
没有使用deldot函数
# deldot($file_name) 删除文件名末尾的点

绕过方法

  1. 使用Burpsuite 拦截请求数据包 更改后缀名末尾处 添加“.” (这也是利用win系统的命名规则特性 “.”或空格即为空)
  2. 使用Burpsuite 拦截请求数据包 更改后缀名为.php. . (程序执行逻辑时 会执行两次移除字符串两侧的空白字符,但程序只执行一次,执行一次后留下的后缀名即为.php.)

以上两种方法仅适用于windows系统下 Linux系统不支持

防御方法

  1. 只执行一次trim函数 只清除一次空格
  2. 添加deldot函数 删除文件末尾的点
  3. 白名单防御方法

PASS 8)

$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!';
}
}

源码分析

$file_name = trim($_FILES['upload_file']['name']);

$file_ext = trim($file_ext); //首尾去空
执行了两次首尾去空
没有对流文件::$DATA进行过滤

绕过方法

  1. 为文件后缀名添加::$DATA
  2. 改变后缀名格式 让程序执行逻辑时 对.和空格做一次移除操作 保留下来的即为可用执行文件

防御方法

  1. 只使用一次trim移除函数
  2. 限制过滤流文件::$DATA
  3. 限制上传文件格式(白名单防御方法)

PASS 9)

$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
$file_ext = str_ireplace('::$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!';
}
}

源码分析

$file_name = trim($_FILES['upload_file']['name']);

$file_ext = trim($file_ext); //首尾去空
执行了两次首尾去空

绕过方法

  1. 改变后缀名格式 让程序执行逻辑时 对.和空格做一次移除操作 保留下来的即为可用执行文件

  2. 即xx.php. . ---> xx.php.

防御方法

  1. 只使用一次trim移除函数
  2. 限制上传文件格式(白名单防御方法)

PASS 10)

$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);
$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!';
}
}

源码分析

$file_name = str_ireplace($deny_ext,"", $file_name);

这里将上传的文件名中包含不允许的后缀名替换为空 得到$file_name
如果上传的文件名中一旦包含php asp jsp 等字符都会被替换为空达到不能正常执行shell程序的作用

绕过方法

  1. 双写绕过 BP拦截更改后缀名为.pphphp

  2. 即xx.pphpphp --识别到php 替换为空-> xx.php

防御方法

  1. 使用完整的黑名单过滤方法 过滤点、空格、大小写、流文件、htaccess分布式配置文件
  2. 使用白名单防御方法 只允许 想要进入的文件格式

⭐PASS1-10 总结过滤后缀名

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'];//获取文件名
$file_name = deldot($file_name);//删除文件名末尾的点 【没有利用在后缀名添加.】
$file_ext = strrchr($file_name, '.');//获取后缀名
$file_ext = strtolower($file_ext); //转换为小写 【没有利用 大小写绕过】
$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA 【没有利用在后缀名添加::4DATA】
$file_ext = trim($file_ext); //首尾去空【没有利用在后缀名添加空格】

PASS 11)

$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!";
}
}

源码分析

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

通过get传入的参数 拼接至url中

绕过方法

  1. GET %00截断(通过burpsuite 实现)

image.png

防御方法

1.验证图片文件真实性

2.不使用请求方式接收参数方式 将其拼接至url

PASS 12)

$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!";
}
}

源码分析

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

通过POST传入的参数 拼接至url中

绕过方法

  1. POST 00截断(通过burpsuite 实现)

image.png

防御方法

1.验证图片文件真实性

2.不使用请求方式接收参数方式 将其拼接至url

PASS 13)

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!";
}
}
}

源码分析

通过观察源码

  1. 可知文件被打开时被验证了文件头2个字节(16位)

  2. 使用 switch……case……语句判断文件头16位编号 以验证图片文件的真实性

  3. 常用文件的文件头如下(16进制):

jpg文件头:FFD8FFE0或FFD8FFE1或FFD8FFE8

gif文件头:47494638PNG
png文件头:89504E47

绕过方法

使用文件包含漏洞解析制作的图片马中包含的php执行的webshell语句

图片马制作方法:
copy 1.png/b + 2.php/a 3.png
以二进制bin打开1.png(真实图片) 用ascii编码打开2.php(webshell.php)
把两者相加,获得3.png

防御方法

防御其他漏洞

PASS 14)

function isImage($filename){
$types = '.jpeg|.png|.gif';
if(file_exists($filename)){
$info = getimagesize($filename);
$ext = image_type_to_extension($info[2]);
if(stripos($types,$ext)>=0){
return $ext;
}else{
return false;
}
}else{
return false;
}
}
$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){
$temp_file = $_FILES['upload_file']['tmp_name'];
$res = isImage($temp_file);
if(!$res){
$msg = "文件未知,上传失败!";
}else{
$img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").$res;
if(move_uploaded_file($temp_file,$img_path)){
$is_upload = true;
} else {
$msg = "上传出错!";
}
}
}

源码分析

$info = getimagesize($filename); //获取图片的真实大小和信息

image_type_to_extension($info[2]) //获取文件的文件头

验证文件的真实类型

如果传入的不是图片就会报错

绕过方法

  1. 使用图片马+文件包含漏洞

防御方法

PASS 15)

function isImage($filename){
//需要开启php_exif模块
$image_type = exif_imagetype($filename);
switch ($image_type) {
case IMAGETYPE_GIF:
return "gif";
break;
case IMAGETYPE_JPEG:
return "jpg";
break;
case IMAGETYPE_PNG:
return "png";
break;
default:
return false;
break;
}
}
$is_upload = false;
$msg = null;
if(isset($_POST['submit'])){
$temp_file = $_FILES['upload_file']['tmp_name'];
$res = isImage($temp_file);
if(!$res){
$msg = "文件未知,上传失败!";
}else{
$img_path = UPLOAD_PATH."/".rand(10, 99).date("YmdHis").".".$res;
if(move_uploaded_file($temp_file,$img_path)){
$is_upload = true;
} else {
$msg = "上传出错!";
}
}
}

源码分析

exif_imagetype() //获取图像信息和图像类型

验证真实文件类型
如果传入的不是真实图片就会报错

绕过方法

  1. 图片马+文件包含漏洞组合拳

防御方法

PASS 16)

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])){
// 获得上传文件的基本信息,文件名,类型,大小,临时文件路径
$filename = $_FILES['upload_file']['name'];
$filetype = $_FILES['upload_file']['type'];
$tmpname = $_FILES['upload_file']['tmp_name'];
$target_path=UPLOAD_PATH.'/'.basename($filename);
// 获得上传文件的扩展名
$fileext= substr(strrchr($filename,"."),1);
//判断文件后缀与类型,合法才进行上传操作
if(($fileext == "jpg") && ($filetype=="image/jpeg")){
if(move_uploaded_file($tmpname,$target_path)){
//使用上传的图片生成新的图片
$im = imagecreatefromjpeg($target_path);
if($im == false){
$msg = "该文件不是jpg格式的图片!";
@unlink($target_path);
}else{
//给新图片指定文件名
srand(time());
$newfilename = strval(rand()).".jpg";
//显示二次渲染后的图片(使用用户上传图片生成的新图片)
$img_path = UPLOAD_PATH.'/'.$newfilename;
imagejpeg($im,$img_path);
@unlink($target_path);
$is_upload = true;
}
} else {
$msg = "上传出错!";
}
}else if(($fileext == "png") && ($filetype=="image/png")){
if(move_uploaded_file($tmpname,$target_path)){
//使用上传的图片生成新的图片
$im = imagecreatefrompng($target_path);
if($im == false){
$msg = "该文件不是png格式的图片!";
@unlink($target_path);
}else{
//给新图片指定文件名
srand(time());
$newfilename = strval(rand()).".png";
//显示二次渲染后的图片(使用用户上传图片生成的新图片)
$img_path = UPLOAD_PATH.'/'.$newfilename;
imagepng($im,$img_path);
@unlink($target_path);
$is_upload = true;
}
} else {
$msg = "上传出错!";
}
}else if(($fileext == "gif") && ($filetype=="image/gif")){
if(move_uploaded_file($tmpname,$target_path)){
//使用上传的图片生成新的图片
$im = imagecreatefromgif($target_path);
if($im == false){
$msg = "该文件不是gif格式的图片!";
@unlink($target_path);
}else{
//给新图片指定文件名
srand(time());
$newfilename = strval(rand()).".gif";
//显示二次渲染后的图片(使用用户上传图片生成的新图片)
$img_path = UPLOAD_PATH.'/'.$newfilename;
imagegif($im,$img_path);
@unlink($target_path);
$is_upload = true;
}
} else {
$msg = "上传出错!";
}
}else{
$msg = "只允许上传后缀为.jpg|.png|.gif的图片文件!";
}
}

源码分析

imagecreatefromjpeg() 二次渲染图片 将上传的图片渲染生成新的图片 压缩处理渲染处理,导致用户上传的图片马被改变,无法使用

(类似微信朋友圈会对图片进行压缩)
在压缩的时候执行半压缩 只执行了压缩清晰图
微信QQ微博是全压缩

--》low imagecreatefromjpeg

--》high 谷歌的图像压缩算法

绕过方法

  1. 上传图片马
  2. 下载图片马链接

https://wwe.lanzoui.com/iFSwwn53jaf

使用特殊的gif,找到在渲染前后不会改变的文件位置,使用webshell链接

防御方法

PASS 17)

$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!';
}
}

源码分析

strrpos()获取字符串最后一个位置

_substr_函数在oracle中使用表示被截取的字符串或字符串表达式

  1. 取出文件得后缀名1.png

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

  1. 上传文件 1.png 传到 upload/1.png

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

  1. if(in_array($file_ext,$ext_arr))

判断后缀名

4.$img_path = UPLOAD_PATH . '/'. rand(10, 99).date("YmdHis").".".$file_ext;
如果是'jpg','png','gif' 文件则上传成功 反之则unlink删除文件

总结上传原理:

条件竞争漏洞
因为PASS17 是先上传再判断,所以加快上传速度和访问速度,进行竞争访问,如果竞争访问速度快过php删除的速度,即可完成漏洞利用

绕过方法

  1. BP爆破 空爆破

image.png

image.png

使用burpsuite爆破模块 高速 上传 webshell.php

使用burpsuite爆破模块 快速 访问 webshell.php

webshell玩法

  1. 执行单一命令 利用漏洞在路径中生成新的webshell
<?php
file_put_contents('a.php','eval($_REQUEST['kio'])',LOCK_EX);
?>
  1. 执行单一命令 利用漏洞在路径中执行命令
<?php system('whoami'); ?>

防御方法

PASS 18)

//index.php
$is_upload = false;
$msg = null;
if (isset($_POST['submit']))
{
require_once("./myupload.php");
$imgFileName =time();
$u = new MyUpload($_FILES['upload_file']['name'], $_FILES['upload_file']['tmp_name'], $_FILES['upload_file']['size'],$imgFileName);
$status_code = $u->upload(UPLOAD_PATH);
switch ($status_code) {
case 1:
$is_upload = true;
$img_path = $u->cls_upload_dir . $u->cls_file_rename_to;
break;
case 2:
$msg = '文件已经被上传,但没有重命名。';
break;
case -1:
$msg = '这个文件不能上传到服务器的临时文件存储目录。';
break;
case -2:
$msg = '上传失败,上传目录不可写。';
break;
case -3:
$msg = '上传失败,无法上传该类型文件。';
break;
case -4:
$msg = '上传失败,上传的文件过大。';
break;
case -5:
$msg = '上传失败,服务器已经存在相同名称文件。';
break;
case -6:
$msg = '文件无法上传,文件不能复制到目标目录。';
break;
default:
$msg = '未知错误!';
break;
}
}
//myupload.php
class MyUpload{
......
......
......
var $cls_arr_ext_accepted = array(
".doc", ".xls", ".txt", ".pdf", ".gif", ".jpg", ".zip", ".rar", ".7z",".ppt",
".html", ".xml", ".tiff", ".jpeg", ".png" );
......
......
......
/** upload()
**
** Method to upload the file.
** This is the only method to call outside the class.
** @para String name of directory we upload to
** @returns void
**/
function upload( $dir ){
$ret = $this->isUploadedFile();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->setDir( $dir );
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->checkExtension();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->checkSize();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
// if flag to check if the file exists is set to 1
if( $this->cls_file_exists == 1 ){
$ret = $this->checkFileExists();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
}
// if we are here, we are ready to move the file to destination
$ret = $this->move();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
// check if we need to rename the file
if( $this->cls_rename_file == 1 ){
$ret = $this->renameFile();
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
}
// if we are here, everything worked as planned :)
return $this->resultUpload( "SUCCESS" );
}
......
......
......
};

源码分析

对文件先上传再重命名

如果上传速度过快 php可能反应不过来

绕过方法

利用条件竞争漏洞批量上传文件

防御方法

PASS 19)

$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 = $_POST['save_name'];
$file_ext = pathinfo($file_name,PATHINFO_EXTENSION);
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 = '禁止保存为该类型文件!';
}
} else {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}

源码分析

CVE-2015-2348 00截断

image.png

绕过方法

使用00截断方法

防御方法

PASS 20)

$is_upload = false;
$msg = null;
if(!empty($_FILES['upload_file'])){
//检查MIME
$allow_type = array('image/jpeg','image/png','image/gif');
if(!in_array($_FILES['upload_file']['type'],$allow_type)){
$msg = "禁止上传该类型文件!";
}else{
//检查文件名
$file = empty($_POST['save_name']) ? $_FILES['upload_file']['name'] : $_POST['save_name'];
if (!is_array($file)) {
$file = explode('.', strtolower($file));
}
$ext = end($file);
$allow_suffix = array('jpg','png','gif');
if (!in_array($ext, $allow_suffix)) {
$msg = "禁止上传该后缀文件!";
}else{
$file_name = reset($file) . '.' . $file[count($file) - 1];
$temp_file = $_FILES['upload_file']['tmp_name'];
$img_path = UPLOAD_PATH . '/' .$file_name;
if (move_uploaded_file($temp_file, $img_path)) {
$msg = "文件上传成功!";
$is_upload = true;
} else {
$msg = "文件上传失败!";
}
}
}
}else{
$msg = "请选择要上传的文件!";
}

源码分析

待我得空了回来填空

绕过方法

防御方法

总结防御方法(不考虑文件包含的存在):

  1. 对象存储服务器

(将用户上传的文件,放置专用的服务器,和网站本身服务器没有任何关系 大厂常用方法)

  1. 检测content-type (如果是上传图片 检测是否为image/png;image/jpg;image/png)
  2. 检测后缀名 (合规的后缀名检测是无法绕过的)
  3. 二次渲染 (对上传的图片进行压缩或处理 合规的渲染可以防御)
  4. 内容检测 (获取文件信息,判断目标不是允许的文件时会直接报错)
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