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news 2025/9/2 11:26:10

less1

(js验证)

我们上传PHP的发现不可以，只能是jpg，png，gif（白名单限制了）

我们可以直接去修改限制

在查看器中看到使用了onsubmit这个函数，触发了鼠标的单击事件，在表单提交后马上调用了return checkFile这个函数对上传的文件进行检查

把onsubmit这个直接删除掉即可。当提交表单时执行一段 JavaScript。它只认true或者false.如果不返回值，则默认为true

上传同样的文件，蚁剑链接即可

我们也可以直接去抓包修改

修改好之后就用蚁剑连接就可以了

less2

绕过MIMETYPE

MIME：多用途互联网邮件扩展协议。用途为根据文件后缀名判断文件类型，用什么应用程序打开，但是在这里是根据文件类型判断后缀名。$_FILES['myfile']['type']文件的MIME类型，需要浏览器提供该信息的支持，例如"image/gif"MIME 给出的是文件的MIME信息，此信息可以用来在HTTP Conten-type 头信息中发送正确的信息，如：header("Cotent-type:image/gif")

知道这一关是MIME验证，就是会检查求情包，只对文件类型（type）进行了验证，必须要是image/jpeg或者image/png或者image/gif的格式，没有对后缀进行验证，只需要使用bp抓包将Content-Type:的参数修改成image/jpeg或者image/png或者image/gif其中的一种，进行绕过就好

分类

最常见的还是image

我们也是直接看看php可不可以，不可以我们抓包看看，png改成php，再访问就可以了，这里是没有改类型，而是改后缀

重新上传3.php，mm为cmd

less3

任务

上传一个脚本文件到服务器，并能成功执行。

$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！';}
}

禁止上传.asp|.aspx|.php|.jsp后缀文件，过滤不严格，用.phtml .php5 .pht进行绕过

less4

任务

拿到一个shell

提示

禁止上传.php|.php5|.php4|.php3|.php2|php1|.html|.htm|.phtml|.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后缀文件！

可以看到这道题被限制的太多了

上传.htaccess文件看看

.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，可以实现:网页301重定向、自定义404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

双引号即后面需要上传的

先上传 .htaccess 成功后再上传 .png文件

也就是将png文件当作php文件执行

less5

任务

上传一个webshell到服务器

提示

先尝试hatccess，提示却说此文件也被限制了，

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 = 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！';}
}

可以和前面的对比一下看看

第五关比第四关少了strtolower，这说明我们可以尝试大小写绕过

$file_ext = strtolower($file_ext); //转换为小写

上传shell.Php，上传成功

less6

任务

拿到一个shell服务器

$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {if (file_exists(UPLOAD_PATH)) {$deny_ext = array(".php",".php5",".php4",".php3",".php2",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".htaccess",".ini");$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！';}
}

也是有黑名单，但是缺少strtolower，说明可以尝试大小写绕过

还有发现第六关没有