基于文件后缀名的绕过
同理，我们先看源码$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
if (file_exists($UPLOAD_ADDR)) {
$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, $deny_ext)) {
if (move_uploaded_file($_FILES['upload_file']['tmp_name'], $UPLOAD_ADDR. '/' . $_FILES['upload_file']['name'])) {
$img_path = $UPLOAD_ADDR .'/'. $_FILES['upload_file']['name'];
$is_upload = true;
}
} else {
$msg = '不允许上传.asp,.aspx,.php,.jsp后缀文件！';
}
} else {
$msg = $UPLOAD_ADDR . '文件夹不存在,请手工创建！';
}
}
从源码中我们可以看到，当前禁止了asp aspx php jsp等常见的后缀名。此时我们用BURP截包改包即可。
只需要将后缀名php改为phtml即可。
如图，成功上传，获得shell
更另类的文件绕过
先看源码$is_upload = false;
$msg = null;
if (isset($_POST['submit'])) {
if (file_exists($UPLOAD_ADDR)) {
$deny_ext = array(".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");
$file_name = trim($_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, $deny_ext)) {
if (move_uploaded_file($_FILES['upload_file']['tmp_name'], $UPLOAD_ADDR . '/' . $_FILES['upload_file']['name'])) {
$img_path = $UPLOAD_ADDR . $_FILES['upload_file']['name'];
$is_upload = true;
}
} else {
$msg = '此文件不允许上传!';
}
} else {
$msg = $UPLOAD_ADDR . '文件夹不存在,请手工创建！';
}
}
从这里，我们看到限制的文件包含了我们常用的所有文件。
".php",".php5",".php4",".php3",".php2","php1",".html",".htm",".phtml",".pHp",".pHp5",".pHp4",".pHp3"
同理，还是很简单，我们仍需burp改包就可以了。
将php改为phP或者pHP即大小写组合。
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