【檔案上傳繞過】五、檔案字尾大小寫繞過

文章目錄

• • • • 一、黑名單
      • 二、源碼
      • 三、大小寫繞過

一、黑名單

本pass禁止上傳.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|.htaccess字尾檔案！

二、源碼

$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);//删除檔案名末尾的點
        $file_ext = strrchr($file_name, '.');
        $file_ext = str_ireplace('::$DATA', '', $file_ext);//去除字元串::$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 = '上傳出錯！';
            }
        } else {
            $msg = '此檔案類型不允許上傳！';
        }
    } else {
        $msg = UPLOAD_PATH . '檔案夾不存在,請手工建立！';
    }
}
           

通過檢視源碼可以發現，雖然設定了黑名單對常見的字尾進行過濾，但并未對字尾名大小寫進行統一。可以利用大小寫進行繞過。

例如：.phP

三、大小寫繞過

準備木馬檔案以

.phP

為字尾

上傳檔案

複制圖檔位址進行通路