uplload 通关纪实 pass8

Posted 2022-12-10 安全界 的彭于晏

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。并且Windows系统下，文件后缀名最后一个点会被自动去除。

源代码如下：

$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']);
        $file_ext = strrchr($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！';
    

上传一个php文件，并用burpsuite抓包：

发送到repeater模块，在8.php后面加上一个点，然后再点击Go，如下图所示，成功上传：

用菜刀连接，并输入相应的密码：

成功访问到：