参考链接:
- 文件上传与upload-labs(大佬的wp)
- 常见php函数
- 变形PHP一句话
- Pass-17参考
实验环境:
- 靶机:upload-labs
- 个人所需能力:PHP代码审计、文件上传绕过
- 物理机系统:windows10 + Ubuntu
- php环境:php7.0.10
- 中间件:Apache2.4.23
- 数据库:mysql5.7.14
- waf:安全狗4.0(并未使用,喜欢挑战的可以开启)
Pass-01(禁用js)
这一关使用的是前端js验证
方法一:使用NoScript插件禁用js
方法二:使用burp抓包修改文件后缀
Pass-02(绕过Content-type验证)
这一关只验证Content-type
方法一:burp抓包改后缀即可
$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!';
}
}
Pass-03(后缀黑名单)
这一关使用黑名单对后缀名进行过滤,并对上传文件名进行改写(无法使用.htaccess,会在前面加上文件名)
方法一:fuzz上传其他php后缀,这里我上传的是shell.php3
常见的php后缀还有.php
.phtml
.phps
.php5
.pht
等
$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!';
}
}
?>
Pass-04(【Apache特性】.htaccess解析绕过)
这一关黑名单,可以在后端对上传文件后缀名进行黑名单处理
方法一:
- 利用apache的特性,上传.htaccess
- 配置文件httpd.conf需要:1.开启mod_rewrite模块 2.AllowOverride All
- 然后上传shell.jpg
.htaccess文件内容:
SetHandler application/x-httpd-php
或者
AddType application/x-httpd-php .jpg
$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",".ini");
$file_name = trim($_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!';
}
}
?>
Pass-05
这一关黑名单,后台检测上传文件的后缀,还限制了
.htaccess
,同时使用strtolower()
函数将文件后缀统一小写,无法使用大小写绕过
知识补充:
.user.ini
类似于.htaccess但是应用范围更广,只要是以fastcgi运行的php都可以用它来动态的局部修改php.ini中的配置
方法一:使用.user.ini绕过
- 查看提示:上传目录中有一个
readme.php
的文件- 上传文件内容为
auto_prepend_file=1.gif
的.user.ini
。
这行语句的作用:所有的php文件都自动包含1.gif文件。.user.ini相当于一个用户自定义的php.ini。- 上传包含一句话内容的
1.gif
# 1.gif 1234GIF89 # gif头部 # php一句话
- 休息3--5分钟喝杯茶,等待.user.ini被重新加载
- 使用蚁剑连接
readme.php
(此时该文件会自动包含1.gif
),密码为一句话的密码,进行getshell(连不上就是你环境问题了)
$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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-06
这一关同样是后端黑名单,同时过滤掉.htaccess和.ini。但是没有使用strtolower()函数,可以使用大小写绕过黑名单
方法一:上传
shell.PHp
,使用蚁剑连接webshell
if (isset($_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",".ini");
$file_name = trim($_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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-07
这一关黑名单,没有使用trim()去除空格,可以使用空格绕过黑名单
方法一:抓包,修改上传文件名
shell.php
(注意这里有个空格)
if (isset($_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",".ini");
$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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-08
这一关黑名单,没有使用deldot()过滤文件名末尾的点,可以使用文件名后加
.
进行绕过
方法一:上传
shell.php.
,使用蚁剑连接webshell
if (isset($_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",".ini");
$file_name = trim($_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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-09
这一关黑名单,没有对::$DATA进行处理,可以使用::$DATA绕过黑名单
补充知识:php在window的时候如果文件名+"::$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.
方法一:上传shell.php::$DATA,使用蚁剑连接shell.php(注意连接路径不要加上::$DATA)
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",".ini");
$file_name = trim($_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!';
}
}
?>
Pass-10
这一关黑名单,最后上传路径直接使用文件名进行拼接,而且只对文件名进行
$file_name = deldot($file_name)
操作去除文件名末尾的点,构造后缀绕过黑名单
补充知识:deldot()函数从后向前检测,当检测到末尾的第一个点时会继续它的检测,但是遇到空格会停下来
方法一:上传
shell.php. .
,使用蚁剑连接shell.php.
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",".ini");
$file_name = trim($_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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-11
这一关黑名单,使用
str_ireplace()
函数寻找文件名中存在的黑名单字符串,将它替换成空(即将它删掉),可以使用双写绕过黑名单
补充知识:
str_ireplace(find,replace,string,count)
函数替换字符串中的一些字符(不区分大小写)
方法一:上传
shell.phphpp
,使用蚁剑连接shell.php
if (isset($_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","ini");
$file_name = trim($_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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-12
这一关白名单,最终文件的存放位置是以拼接的方式,可以使用%00截断,但需要php版本<5.3.4,并且magic_quotes_gpc关闭。
原理:php的一些函数的底层是C语言,而move_uploaded_file就是其中之一,遇到0x00会截断,0x表示16进制,URL中%00解码成16进制就是0x00。
知识补充:
strrpos(string,find[,start])
函数查找字符串在另一字符串中最后一次出现的位置(区分大小写)。
substr(string,start[,length])
函数返回字符串的一部分(从start开始 [,长度为length])
magic_quotes_gpc 着重偏向数据库方面,是为了防止sql注入,但magic_quotes_gpc开启还会对$_REQUEST, $_GET,$_POST,$_COOKIE 输入的内容进行过滤
方法一:抓包修改上传路径,使用蚁剑连接路径中的php文件
if(isset($_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{
$msg = "只允许上传.jpg|.png|.gif类型文件!";
}
}
?>
Pass-13
这一关白名单,文件上传路径拼接生成,而且使用了post发送的数据进行拼接,我们可以控制post数据进行0x00截断绕过白名单
补充知识:POST不会对里面的数据自动解码,需要在Hex中修改。
方法一:
- 抓包修改post{‘save_path’: '../upload/upload-13.php%00'}
- 修改hex中php后面的子节为00
- 使用蚁剑连接upload-13.php
if(isset($_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 {
$msg = "只允许上传.jpg|.png|.gif类型文件!";
}
}
?>
Pass-14
这一关会读取判断上传文件的前两个字节,判断上传文件类型,并且后端会根据判断得到的文件类型重命名上传文件
使用图片码 + 文件包含
绕过
补充知识:
1.Png图片文件包括8字节:89 50 4E 47 0D 0A 1A 0A。即为 .PNG….。
2.Jpg图片文件包括2字节:FF D8。
3.Gif图片文件包括6字节:47 49 46 38 39|37 61 。即为 GIF89(7)a。
4.Bmp图片文件包括2字节:42 4D。即为 BM。
方法一:
cmd使用copy 1.jpg/b+1.php 2.jpg
制作图片码,上传图片码
找到上一级目录有一个include.php
文件,存在文件包含漏洞 (别问我怎么找到的,现实中随缘)
构造url:include.php?file=upload/shell.jpg
使用蚁剑连接该url
function getReailFileType($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 {
$msg = "上传出错!";
}
}
}
?>
Pass-15
方法一:参考十四关,上传图片码,使用文件包含漏洞解析图片码
知识补充:
getimage()函数
返回一个数组,索引 2 给出的是图像的类型,返回的是数字,其中1 = GIF,2 = JPG,3 = PNG,4 = SWF,5 = PSD,6 = BMP,7 = TIFF(intel byte order),8 = TIFF(motorola byte order),9 = JPC,10 = JP2,11 = JPX,12 = JB2,13 = SWC,14 = IFF,15 = WBMP,16 = XBM
image_type_to_extension()
获取图片扩展名
function isImage($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 {
$msg = "上传出错!";
}
}
}
?>
Pass-16
参考十四关,上传图片码,使用文件包含漏洞解析图片码
知识补充:
exif_imagetype()读取一个图像的第一个字节并检查其签名。
返回值与getimage()函数返回的索引2相同,但是速度比getimage快得多。需要开启php_exif模块。
function isImage($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 {
$msg = "上传出错!";
}
}
}
?>
Pass-17
这一关对上传图片进行了后端二次渲染,需要找到渲染后没有发生变化的地方,添加一句话,通过文件包含漏洞执行一句话,使用蚁剑进行连接
补充知识:
- 二次渲染:后端重写文件内容
- basename(path[,suffix]) ,没指定suffix则返回后缀名,有则不返回指定的后缀名
strrchr(string,char)
函数查找字符串在另一个字符串中最后一次出现的位置,并返回从该位置到字符串结尾的所有字符。- imagecreatefromgif():创建一块画布,并从 GIF 文件或 URL 地址载入一副图像
imagecreatefromjpeg():创建一块画布,并从 JPEG 文件或 URL 地址载入一副图像
imagecreatefrompng():创建一块画布,并从 PNG 文件或 URL 地址载入一副图像
imagecreatefromwbmp():创建一块画布,并从 WBMP 文件或 URL 地址载入一副图像
imagecreatefromstring():创建一块画布,并从字符串中的图像流新建一副图像
方法一(gif):
- 上传正常的gif图片,下载回显的图片
- 对比两个gif图片内容,找到相同的地方
- 插入php一句话,上传带有一句话的gif图片
- 利用文件包含漏洞,使用蚁剑连接
方法二(png):
- 通过大牛的脚本生成一个1.png(将一句话插入到png的IDAT数据块中)
- 使用蚁剑进行连接(需要一点技巧)
# 1.png生成脚本
方法三(jpg):(未使用成功)
- 使用国外大牛写的脚本jpg_payload.php
- 运行
php jpg_payload.php 1.jpg
- 上传生成的payload_1.jpg
- 利用文件包含或者.htaccess或.user.ini,使用蚁剑进行连接
方法四(if语句造成条件竞争):
- 代码中有一个if判断
if(move_uploaded_file($tmpname,$target_path))
这里会产生条件竞争漏洞
绕过原理:不断上传文件,在文件还没被删除前去读取文件,解析里面的php代码(生成一个新的PHP文件),实现绕过
- 将
');?>
放进gif文件不会被二次渲染改变的地方(假设文件名shell.gif)- 上传shell.gif,使用burp抓包 --> 发送到repeater
- 不断发包,同时快速访问还没改名的文件,利用文件包含漏洞解析上传的文件
../include.php?file=upload/shell.gif
- 只要你单身手速够快,在include.php同一目录下就会生成一个2.php
- 使用蚁剑连接这个2.php
if (isset($_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{
$msg = "只允许上传后缀为.jpg|.png|.gif的图片文件!";
}
}
?>
Pass-18
这一关白名单(可以使用第十七关的方法四),源码中存在判断语句
if(move_uploaded_file($temp_file, $upload_file))
,存在条件竞争漏洞
补充知识:
move_uploaded_file(file[,newloc]),该函数将上传的文件移动到新位置。若成功,则返回 true,否则返回 false。
方法一:
- 将
');?>
插入到gif图片中(假设文件名shell.gif)- 上传shell.gif,使用burp进行抓包 --> 发送到repeater
- 不断发包,同时快速访问还没改名的文件,利用文件包含漏洞解析上传的文件
../include.php?file=upload/shell.gif
- 只要你单身手速够快,在include.php同一目录下就会生成一个2.php
- 使用蚁剑连接这个2.php
if(isset($_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{
$msg = '上传出错!';
}
}
?>
Pass-19(没有成功)
这一关白名单,同样利用条件竞争漏洞。
上传检查流程主要是看./myupload.php
文件(这里只给出myupload.php
的关键函数)
需要注意上传路径,这一关直接用.
进行拼接得到文件名(前面关卡都是用.'/'.
拼接路径和文件名的)
方法一: (参考十七、十八关解法)
- 将
');?>
插入到gif图片中(假设文件名shell.gif)- 上传
shell.gif
,使用burp进行抓包 --> 发送到repeater- 不断发包,同时快速访问还没改名的文件,利用文件包含漏洞解析上传的文件
../include.php?file=./uploadshell.gif
注意访问的文件名- 只要你单身手速够快,在include.php同一目录下就会生成一个
2.php
- 使用蚁剑连接这个
2.php
# myupload.php
# 传递到upload函数中的$dir="../upload",末尾没有加/,直接拼接,导致临时保存和重命名后文件保存在include.php同一目录下,且文件名前面都有upload字样
function upload( $dir ){
$ret = $this->isUploadedFile(); # 检查是否有文件要上传
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->setDir( $dir ); # 检查上传目录是否可写
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->checkExtension(); # 检查上传文件后缀是否合法
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
$ret = $this->checkSize(); # 检查上传文件大小
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(); # 检查文件是否已经存在
if( $ret != 1 ){
return $this->resultUpload( $ret );
}
}
// if we are here, we are ready to move the file to destination
$ret = $this->move(); # 保存上传文件到临时目录中(关键)
# if( move_uploaded_file( $this->cls_tmp_filename, $this->cls_upload_dir . $this->cls_filename ) == false )
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 $this->resultUpload( "SUCCESS" );
}
if (isset($_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:
$msg = '未知错误!';
break;
}
}
?>
Pass-20
这一关黑名单,发现没有过滤.ini,可以使用.user.ini进行绕过。
验证过程:判断上传路径是否存在 -->pathinfo()
函数获取POST参数(保存文件名)的后缀名 --> 判断后缀是否合法(.ini
.php.
) --> 将上传文件名重命名为POST请求中的文件名
补充知识:
pathinfo()函数,当文件后缀名末尾为.
时,获取到的文件后缀名为空值。当文件名出现多个.
,函数判断最后一个.
后面才是后缀名。
方法一:
- 上传后缀名为
shell.php.
的文件,保存文件名(POST参数)也设置为shell.php.
- 使用蚁剑进行连接
方法二:上传.user.ini进行绕过(具体操作参考第五关)
if (isset($_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");
/*
$file_name = trim($_POST['save_name']);
$file_name = deldot($file_name);//删除文件名末尾的点
$file_ext = pathinfo($file_name,PATHINFO_EXTENSION);
$file_ext = strtolower($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
*/
$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 {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
Pass-21
这一关白名单,
验证过程:
--> 验证上传路径是否存在
--> 验证['upload_file']的content-type是否合法(可以抓包修改)
--> 判断POST参数是否为空定义$file变量(关键:构造数组绕过下一步的判断)
--> 判断file不是数组则使用explode('.', strtolower($file))
对file进行切割,将file变为一个数组
--> 判断数组最后一个元素是否合法
--> 数组第一位和$file[count($file) - 1]
进行拼接,产生保存文件名file_name
--> 上传文件
补充知识:
- explode(separator,string[,limit]) 函数,使用一个字符串分割另一个字符串,并返回由字符串组成的数组。
- end(array)函数,输出数组中的当前元素和最后一个元素的值。
- reset(array)函数,把数组的内部指针指向第一个元素,并返回这个元素的值
- count(array)函数,计算数组中的单元数目,或对象中的属性个数
方法一:
- 上传shell.php和POST参数,抓包
- 修改content-type
- 修改POST参数为数组类型,索引[0]为shell.php,索引[2]为jpg|png|gif。
只要第二个索引不为1,$file[count($file) - 1]
就等价于$file[2-1],值为空- 发包,使用蚁剑连接../upload/shell.php
if (isset($_POST['submit'])) {
if (file_exists(UPLOAD_PATH)) {
$is_upload = false;
$msg = null;
if(!empty($_FILES['upload_file'])){
//mime check
$allow_type = array('image/jpeg','image/png','image/gif');
if(!in_array($_FILES['upload_file']['type'],$allow_type)){
$msg = "禁止上传该类型文件!";
}else{
//check filename
$file = empty($_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!";
}
} else {
$msg = UPLOAD_PATH . '文件夹不存在,请手工创建!';
}
}
?>
文件上传
漏洞成因: 具备上传文件功能的Web等应用,未对用户选择上传的文件进行校验,使得非法用户可通过上传可执行脚本而获取应用的控制权限。
防护与绕过: 通过upload-labs靶场,了解更多的防护与绕过手段。
防御
- 不要暴露上传文件的位置;
- 禁用上传文件的执行权限;
- 黑白名单;
- 对上传的文件重命名,不易被猜测;
- 对文件内容进行二次渲染;
- 对上传的内容进行读取检查;
不同系统有不同的需求,根据系统需求制定特定的防御手段。
(WAF加上防火墙,一键安装解君愁~)
吐槽
- markdown不支持页内跳转= ^ =
别人家的md实现页内跳转
❀❀完结撒花❀❀
(忘了还有waf这个现实级别难度……)
-
写得不好的地方,欢迎各位大表哥私聊斧正!