文件上传 upload-labs
BUUCTF=>Basci=>Upload-Labs-Linux 1
思维导图
客户端 检查
Pass-1 js检查
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;
}
}
1.浏览器（FireFox）禁用js
about:config
2.F12删除掉检查函数
服务端 黑名单
Pass-2 MIME-Type类型
$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 {
$msg = UPLOAD_PATH.'文件夹不存在,请手工创建！';
}
}
这关只对Content-Type:进行了验证
if (($_FILES['upload_file']['type'] == 'image/jpeg') || ($_FILES['upload_file']['type'] == 'image/png') || ($_FILES['upload_file']['type'] == 'image/gif')) {
......
} else {
$msg = '文件类型不正确，请重新上传！';
}
1.修改Content-Type
MIME (Multipurpose Internet Mail Extensions) 是描述消息内容类型的因特网标准。
MIME 消息能包含文本、图像、音频、视频以及其他应用程序专用的数据。
2.Burp改包shell.png =>shell.php
Pass-3 可解析特殊后缀
$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！';
}
}
上传特殊后缀文件，能被php解析，但文件名被改了
1.Proxy->Repater->raw记着改过后的文件名
2.直接就拖图片到搜索框（图片的href就是它保存的位置）
Pass-4 分布式配置文件 .htaccess
$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！';
}
}
$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");
虽然没有过滤pphhpp但它解析出来是文本形式,怎么把它解析成php呢
.htaccess文件(或者"分布式配置文件"）,全称是Hypertext Access(超文本入口)。
概述来说，htaccess文件是Apache服务器中的一个配置文件，它负责相关目录下的网页配置。通过htaccess文件，可以帮我们实现：网页301重定向、自定义404错误页面、改变文件扩展名、允许/阻止特定的用户或者目录的访问、禁止目录列表、配置默认文档等功能。
Unix、Linux系统或者是任何版本的Apache Web服务器都是支持.htaccess的，但是有的主机服务商可能不允许你自定义自己的.htaccess文件。
启用.htaccess，需要修改httpd.conf，启用AllowOverride，并可以用AllowOverride限制特定命令的使用。如果需要使用.htaccess以外的其他文件名，可以用AccessFileName指令来改变。例如，需要使用.config ，则可以在服务器配置文件中按以下方法配置：AccessFileName .config 。
笼统地说，.htaccess可以帮我们实现包括：文件夹密码保护、用户自动重定向、自定义错误页面、改变你的文件扩展名、封禁特定IP地址的用户、只允许特定IP地址的用户、禁止目录列表，以及使用其他文件作为index文件等一些功能。
.htaccess
<FilesMatch "任意后缀木马文件名"
SetHandler application/x-httpd-php
</FilesMatch>
上传shell.hugboy马，蚁剑连接
Pass-5 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！';
}
}
这关删去了此行代码
$file_ext = strtolower($file_ext); //转换为小写
Pass-6 空格绕过 （windows）
if (!in_array($file_ext, $deny_ext)) {
......
} else {
$msg = '此文件不允许上传';
}
代码比较时会带上空格去和黑名单匹配，burp改包文件名shell.php windows会自动忽略后面的空格
识别为shell.php。
Pass-7 点号绕过
这关删去了此行代码
$file_name = deldot($file_name);//删除文件名末尾的点
Burp改包shell.php=>shell.php.
Pass-8 ::$DATA绕过 (windows)
这关删去了此行代码
$file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字符串::$DATA
在window的时候如果文件名+"::$DATA"会把::$DATA之后的数据当成文件流处理,不会检测后缀名，
且保持::$DATA之前的文件名，他的目的就是不检查后缀名
例如:"phpinfo.php::$DATA"Windows会自动去掉末尾的::$DATA变成"phpinfo.php"
Burp改包shell.php=>shell.php::$DATA
Pass-9 点+空格+点 (windows)
虽然有以下检查
$file_name = deldot($file_name);//删除文件名末尾的点
......
$file_ext = trim($file_ext); //首尾去空
但我们Burp改包shell.php=>shell.php. .相当于Pass-7 点号绕过。
Pass-10 双写绕过
$file_name = str_ireplace($deny_ext,"", $file_name);
上传shell.pphphp,shell.phphpp。。。
服务端 白名单
Pass-11 白名单 Get%00 截断（PHP<php.534）
先上传shell.png
Burp改包修改保存目录save_path: shell.php=>shell.php%00
Pass-12 白名单 POST%00 截断（PHP<php.534）
服务端 图片马
图片马上传后,服务器不能解析,我们要结合文件包含漏洞才能利用。
Pass-13 图片马
这关是根据上传文件内容来判断图片类型,具体如下
$file = fopen($filename, "rb");
$bin = fread($file, 2); //只读2字节
fclose($file);
$strInfo = @unpack("C2chars", $bin);//unpack方式解码
$typeCode = intval($strInfo['chars1'].$strInfo['chars2']);//用intval分别把2字节内容转换为10进制后拼接
$fileType = '';
switch($typeCode){ //根据计算出的$typeCode判断图片类型
case 255216:
$fileType = 'jpg';
break;
case 13780:
$fileType = 'png';
break;
case 7173:
$fileType = 'gif';
break;
default:
$fileType = 'unknown';
}
return $fileType;
}
我们构造图片类型正确,但包含shell内容的图片
png和jpg类型构造方式
copy image.png/b + phpinfo.php = pngphpinfo.png
gif类型构造方式（其实只是绕过,并未真正构造）
Pass-14 getimagesize()绕过
绕过方法同Pass-13,只不过换了一种验证图片类型的方式。
function isImage($filename){
$types = '.jpeg|.png|.gif';
if(file_exists($filename)){
$info = getimagesize($filename);//获取图片参数
$ext = image_type_to_extension($info[2]);//索引2代表图片的类型
if(stripos($types,$ext)>=0){
return $ext;
}else{
return false;
}
}else{
return false;
}
}
另:
getimagesize(string $filename [,array &$imageinfo])//获取图像信息，返回一个数组
/*
返回的数组中，索引0：图像宽度像素值
索引1：图像高度像素值
索引2：图像类型，1=GIF，2=JPG，3=PNG，4=SWF，5=PSD，6=BMP，7=TIFF_II，8=TIFF_MM，9=JPC，10=JP2，11=JPX，12=JB2，13=SWC，14=IFF，15=WBMP，16=XBM，17=ICO，18=COUNT
索引3：图像宽度和高度的字符串
索引bits：图像的每种颜色的位数，二进制格式
索引channels：图像的通道值
索引mime：图像的MIME信息
/
image_type_to_extension(int $imagetype [,bool $include_dot = TRUE])//获取图像类型的文件扩展名
/
include_dot是否在扩展名前加点。默认为TRUE
*/
Pass-15 exif_imagetype() 绕过
绕过方法同Pass-13,只不过换了一种验证图片类型的方式。
function isImage($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;
}
}
参考
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