Upload-labs 20关通关笔记
upload-labs是一个使用php语言编写的，专门收集渗透测试和CTF中遇到的各种上传漏洞的靶场。旨在帮助大家对上传漏洞有一个全面的了解。目前一共20关，每一关都包含着不同上传方式。
项目地址：https://github.com/c0ny1/upload-labs
2019年1月13日添加了第20关。
测试环境：
PHP/5.6.27
Apache/2.4.23
windows
Pass-01-js检查
这种直接禁用JS，或者burp改包等等都可以。
Pass-02-只验证Content-type
$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！';
}
}
抓包改Content-Type即可。
Pass-03-黑名单绕过
$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！';
}
}
不允许上传.asp,.aspx,.php,.jsp后缀文件，但是可以上传其他任意后缀
.php .phtml .phps .php5 .pht前提是apache的httpd.conf中有如下配置代码
AddType application/x-httpd-php .php .phtml .phps .php5 .pht或者上传.htaccess文件
需要：1.mod_rewrite模块开启。2.AllowOverride All
文件内容
<FilesMatch "shell.jpg">
SetHandler application/x-httpd-php
</FilesMatch>此时上传shell.jpg文件即可被当作php来解析。
或者
AddType application/x-httpd-php .jpg另外基本上所有的黑名单都可以用Apache解析漏洞绕过。
Pass-04-.htaccess绕过
$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！';
}
}
过滤了各种罕见后缀
$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");
但是没有过滤.htaccess，用上面的方法即可。
Pass-05-大小写绕过
$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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';
}
}
过滤了.htaccess，并且代码中后缀转换为小写被去掉了，因此我们可以上传Php来绕过黑名单后缀。(在Linux没有特殊配置的情况下，这种情况只有win可以，因为win会忽略大小写)
Pass-06-空格绕过
Win下xx.jpg[空格] 或xx.jpg.这两类文件都是不允许存在的，若这样命名，windows会默认除去空格或点
此处会删除末尾的点，但是没有去掉末尾的空格，因此上传一个.php空格文件即可。
Pass-07-点绕过
没有去除末尾的点，因此与上面同理，上传.php.绕过。
Pass-08-::$DATA绕过
NTFS文件系统包括对备用数据流的支持。这不是众所周知的功能，主要包括提供与Macintosh文件系统中的文件的兼容性。备用数据流允许文件包含多个数据流。每个文件至少有一个数据流。在Windows中，此默认数据流称为：$ DATA。
上传.php::$DATA绕过。(仅限windows)
Pass-09-.空格.绕过
move_upload_file的文件名直接为用户上传的文件名，我们可控。且会删除文件名末尾的点，因此我们可以结合Pass-7用.php.空格.绕过。
windows会忽略文件末尾的.和空格。
另外这里发现$_FILES['upload_file']['name']获取的是文件名中/后面的字符串，本来还想用move_uploaded_file会忽略/.的trick绕过。
Pass-10-双写绕过
敏感后缀替换为空，双写.pphphp绕过即可。
Pass-11-00截断
CVE-2015-2348
影响版本：5.4.x<= 5.4.39, 5.5.x<= 5.5.23, 5.6.x <= 5.6.7
exp：move_uploaded_file($_FILES['name']['tmp_name'],"/file.php\x00.jpg");
源码中move_uploaded_file中的save_path可控，因此00截断即可。
Pass-12-略
把Pass-11的GET方式改成了POST，同理。
Pass-13-16-图片马
Pass-13-unpack
上传图片马。
function getReailFileType($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！";
}
}
}
制作图片马
copy smi1e.jpg /b + shell.php /a shell.jpg
Pass-14-getimagesize()
同Pass-13
Pass-15-exif_imagetype()
同Pass-13
Pass-16-二次渲染绕过
$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！";
}
}
判断了后缀名、content-type，以及利用imagecreatefromgif判断是否为gif图片，最后再做了一次二次渲染，绕过方法可以参考先知的文章，写的很详细：https://xz.aliyun.com/t/2657
jpg和png很麻烦，gif只需要找到渲染前后没有变化的位置,然后将php代码写进去,就可以了。
Pass-17-条件竞争
$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！';
}
}
可以看到文件先经过保存，然后判断后缀名是否在白名单中，如果不在则删除，此时可以利用条件竞争在保存文件后删除文件前来执行php文件。
利用bp不断发送上传包和请求包。
成功执行命令：
Pass-18-条件竞争
//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" );
}
......
......
......
}
因为move在rename之前
move操作进行了一次文件保存
然后rename进行了一次更改文件名
因此我们可以通过条件竞争来上传图片马。
Pass-19-/.绕过
$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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建！';
}
}
这里是我在Pass9提到的一个trick，move_uploaded_file会忽略掉文件末尾的/.。但是Pass9中的文件名是从$_FILES['upload_file']['tmp_name']中获取的，这里是用户可控的。
因此构造
当然也可以用move_uploaded_file函数的00截断漏洞绕过。
Pass-20-数组+/.绕过
$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{
$msg = "请选择要上传的文件！";
}
可以发现$file_name经过reset($file) . '.' . $file[count($file) - 1];处理。
如果上传的是数组的话，会跳过$file = explode('.', strtolower($file));。
并且后缀有白名单过滤
$ext = end($file);
$allow_suffix = array('jpg','png','gif');
而最终的文件名后缀取的是$file[count($file) - 1]，因此我们可以让$file为数组。
$file[0]为smi1e.php/，也就是reset($file)，然后再令$file[2]为白名单中的jpg。
此时end($file)等于jpg，$file[count($file) - 1]为空。
而 $file_name = reset($file) . '.' . $file[count($file) - 1];，也就是smi1e.php/.，最终move_uploaded_file会忽略掉/.，最终上传smi1e.php。
解析漏洞
解析漏洞是服务器端中间件的问题，可以根据不同的解析漏洞应用在以上题目的情况中。
可以参考我的另一篇文章：文件解析漏洞总结
后记
虽然大部分都是学过的知识，但是在复现的过程中通过Debug学到了不少之前不知道的东西。