文件上传漏洞——upload-labs(1-10)
前言：文件上传漏洞有很多种绕过技巧，这次就通过upload-labs进行学习
第一关
上传有限制，只让上传JPEG或PNG格式的图片，就先尝试一下抓包修改上传格式的方法看看是否可行
先将一句话木马PHP文件后缀名改为PNG格式，上传拦截抓包
拦截请求包后，将1.png改为1.php，再发包，用菜刀进行连接，在此之前需要知道上传的文件上传到哪个目录下，查看源码查出图片上传路径
路径也知道了，就用菜刀进行连接
连接成功
观察一下第一关的源码
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;
}
}
通过观察只是限制了在上传时的类型，所以中途拦截抓包改格式的方法是完成可行的。
方法：改包绕过上传
第二关
做第二关时发现沿用第一关的方法也是可行的，不过应该不会再考同一个点了
就查看一下源码
$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 {
$msg = UPLOAD_PATH.'文件夹不存在,请手工创建！';
}
}
发现这一段代码判断content-type,那就可以通过修改content-type进行绕过：
if (($_FILES['upload_file']['type'] == 'image/jpeg') || ($_FILES['upload_file']['type'] == 'image/png') || ($_FILES['upload_file']['type'] == 'image/gif'))
抓包将application/octet-stream修改为image/png或image/gif都可以
连接成功
方法：修改content-type进行绕过
第三关
上传PHP文件时，发现有这样的提示
应该是源码中限制了这些文件的后缀名，查看大师傅们的博客发现还可以用
phtml，php3，php4, php5, pht
这些后缀名进行绕过，就来尝试一下，发现连接不上去，查了一下才知道原来前提是apache的httpd.conf中有如下配置代码
AddType application/x-httpd-php .php .phtml .phps .php5 .pht
我这里使用的是phpstudy+windows，即使添加了也不管用，查了大师傅的博客才知道是由于配置原因是解析不了php5等等这些后缀的，所以复现不了，可以在虚拟机中复现这关。
不过也知道了这一关是采用拓展名绕过
查看一下源码
$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']);//trim() 函数移除字符串两侧的空白字符或其他预定义字符
$file_name = deldot($file_name);//删除文件名末尾的点
$file_ext = strrchr($file_name, '.');//strrchr() 函数查找字符串在另一个字符串中最后一次出现的位置，并返回从该位置到字符串结尾的所有字符。
$file_ext = strtolower($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)) {//in_array() 函数搜索数组中是否存在指定的值
$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！';
}
}
观察源码就会发现这里确实采用黑名单来限制
方法：拓展名绕过
第四关
没什么思路，查看一下提示
发现基本上将所有非法的脚本后缀都禁用了，还是黑名单限制，查看一下源码
$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",".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'];
$img_path = UPLOAD_PATH.'/'.$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！';
}
}
果然是将所有非法的脚本后缀都禁用了，但是没有禁用.htaccess，先来了解一下htaccess文件的作用，.htaccess的基本作用及相关语法介绍
在这里使用htaccess文件目的是为了将所有文件都当成php文件来解析
创建一个.htaccess文件
SetHandler application/x-httpd-php
在文件中写入该段代码，上传时将文件名去掉，只要后缀名
上传后，上传图片马，由于连接菜刀麻烦，这里就修改一句话语句为
phpinfo(); ?>
上传图片马成功后，进行查看
解析成功
方法：.htaccess文件进行绕过
第五关
上传.htaccess文件，发现该后缀名也被加入黑名单了
查看源码
$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！';
}
}
通过观察，发现黑名单中限制的后缀名没有将大小写统一，采用大小写方式进行绕过
上传成功，进行查看
方法：大小写绕过
第六关
无论如果改后缀名都无法上传，说明这关代码已经统一了大小写
查看源码
$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！';
}
}
还是采用了黑名单来进行限制，不过与前几关先比较会发现少了这一行代码
$file_ext = trim($file_ext); //首尾去空
那么就可以采用后缀名中加空绕过
在后缀名中加入空格.php空格，再发包，上传成功
方法：后缀名加空绕过
第七关
查看源码
$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！';
}
}
还是黑名单，这次又有什么不一样的，通过与前几关对比发现少了这行代码
$file_name = deldot($file_name);//删除文件名末尾的点
所以可以采用后缀名加.的方式绕过，在这之前，先来了解一下对Windows系统文件命名规则的特殊利用
shell.php. ———-文件名后加点‘.’
shell.php(空格) ———-文件名后加括号空格
shell.php:1.jpg ———-文件名后加冒号’:’
shell.php::$DATA ———-文件名后加NTFS ADS特性::$DATA
shell.php::$DATA…… ———-文件名后::$DATA……
会被windows系统自动去掉不符合规则符号后面的内容。
windows系统文件命名规则的特殊利用
因此我们可以先抓包然后在后缀名后加上.，文件上传时由于不符合windows文件命名规则而将.去掉，从而将.php的文件上传进去
访问
绕过方法：后缀名加.绕过
第八关
查看源码
$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！';
}
}
还是黑名单限制，观察一下与之前有那些不同
发现少了这一段代码
$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA
没有去除字符串::$DATA，根据Windows系统文件命名规则进行抓包修改即可
shell.php::$DATA ———-文件名后加NTFS ADS特性::$DATA
原理和第七关类似
访问成功
绕过方法：后缀名加::$DATA绕过
第九关
查看源码
$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！';
}
}
观察看与前几关的代码有什么不同的地方，发现
$img_path = UPLOAD_PATH.'/'.$file_name;
路径拼接的是处理后的文件名$file_name，而不是$file_ext，也就是说最后保存文件的时候没有重命名而使用的原始的文件名，那相当于$file_name只经过那两段代码的过滤
$file_name = trim($_FILES['upload_file']['name']);//移除字符串两侧的空白字符
$file_name = deldot($file_name);//删除文件名末尾的点
那就可以采用**后缀名（点+空格+点）**的方法来绕过
上传时，代码会先将末尾的.去除，剩余.+空格，利用Windows系统文件命名规则，windows会忽略文件末尾的.和空格，这样即可上传进取
绕过方法：后缀名+.+空格+.进行绕过
第十关
查看源码
$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！';
}
}
#str_ireplace() 函数替换字符串中的一些字符（不区分大小写）
/*str_ireplace(find,replace,string,count)
find 必需。规定要查找的值。
replace 必需。规定替换 find 中的值的值。
string 必需。规定被搜索的字符串。*/
这一段代码将后缀名全部替换成了空
$file_name = str_ireplace($deny_ext,"", $file_name);
之前学习XSS时也碰到这种情况，可以采用双写进行绕过
过滤了php，前后再拼接成PHP
访问成功：
绕过方法：双写绕过
总结：通过这十关又学到了很多文件上传的技巧，下次继续学习后十关，这次先学习到这里。