文件上传漏洞靶场（作者前言）
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
- 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。
- 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
- 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
- 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
- 过滤完整的后端执行后缀名
- 过滤分布式配置文件.htaccess
- 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
- 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
- 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
- 过滤htaccess 限制上传此文件
- 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
- 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
- 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
- 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）
- 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
- 使用BP拦截请求消息 更改后缀名+空格 即.php+%20
防御方法
- 白名单防御法 只允许想要上传进入的文件格式
- 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
- 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)
- 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
- 只执行一次trim函数 只清除一次空格
- 添加deldot函数 删除文件末尾的点
- 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::$DATA进行过滤
绕过方法
- 为文件后缀名添加::$DATA
- 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
- 只使用一次trim移除函数
- 限制过滤流文件::$DATA
- 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
- 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
- 即xx.php. . ---> xx.php.
防御方法
- 只使用一次trim移除函数
- 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
- 双写绕过 BP拦截更改后缀名为.pphphp
- 即xx.pphpphp --识别到php 替换为空-> xx.php
防御方法
- 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
- 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
- GET %00截断（通过burpsuite 实现）
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
- POST 00截断（通过burpsuite 实现）
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 { $msg = "上传出错！"; } } } 源码分析
通过观察源码
- 可知文件被打开时被验证了文件头2个字节（16位）
- 使用 switch……case……语句判断文件头16位编号 以验证图片文件的真实性
- 常用文件的文件头如下(16进制)：
jpg文件头：FFD8FFE0或FFD8FFE1或FFD8FFE8
gif文件头：47494638PNG
png文件头：89504E47
绕过方法
使用文件包含漏洞解析制作的图片马中包含的php执行的webshell语句
图片马制作方法：
copy 1.png/b + 2.php/a 3.png
以二进制bin打开1.png（真实图片） 用ascii编码打开2.php（webshell.php）
把两者相加，获得3.png
防御方法
防御其他漏洞
PASS 14）
function isImage($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（$info[2]） //获取文件的文件头
验证文件的真实类型
如果传入的不是图片就会报错
绕过方法
- 使用图片马+文件包含漏洞
防御方法
PASS 15）
function isImage($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
- 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
- 上传图片马
- 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
- 取出文件得后缀名1.png
$file_ext = substr($file_name,strrpos($file_name,".")+1);
- 上传文件 1.png 传到 upload/1.png
$upload_file = UPLOAD_PATH . '/' . $file_name;
- if(in_array($file_ext,$ext_arr))
判断后缀名
4.$img_path = UPLOAD_PATH . '/'. rand(10, 99).date("YmdHis").".".$file_ext;
如果是'jpg','png','gif' 文件则上传成功 反之则unlink删除文件
总结上传原理：
条件竞争漏洞
因为PASS17 是先上传再判断，所以加快上传速度和访问速度，进行竞争访问，如果竞争访问速度快过php删除的速度，即可完成漏洞利用
绕过方法
- BP爆破 空爆破
使用burpsuite爆破模块 高速 上传 webshell.php
使用burpsuite爆破模块 快速 访问 webshell.php
webshell玩法
- 执行单一命令 利用漏洞在路径中生成新的webshell
<?php file_put_contents('a.php','eval($_REQUEST['kio'])',LOCK_EX); ?> - 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
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
绕过方法
防御方法
总结防御方法（不考虑文件包含的存在）：
- 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）
- 检测content-type （如果是上传图片 检测是否为image/png;image/jpg;image/png）
- 检测后缀名 (合规的后缀名检测是无法绕过的)
- 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）
- 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）
