upload-labs关卡8(基于黑名单的点绕过)通关思路

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前言

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此文章只用于学习和反思巩固文件上传漏洞知识，禁止用于做非法攻击。注意靶场是可以练习的平台，不能随意去尚未授权的网站做渗透测试！！！

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一、回顾上一关知识点

上一关是利用win特性，因为win命名后缀名时，后缀名后面加上空格或点都是等同于原来文件。这一关也是利用win特性进行点绕过。

二、靶场第八关通关思路

• 1、看源代码
• 2、点绕过
• 3、验证文件是否成功上传

1、看源代码

$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",".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！';
    }
}

可以发现这一关同上一关相比多了首尾去空，少了去除末尾的点。那么我们就可以通过命名1.php.进行绕过

2、点绕过

这里我上传123.php文件，然后bp修改文件为123.php.


发现上传成功

3、验证文件是否成功上传

发现上传成功，如果是一句话木马就可以连接菜刀了

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总结

这一关是利用window特性进行点绕过，与前几关的思路一样。此文章是小白自己为了巩固文件上传漏洞而写的，大佬路过请多指教！