一、Javascript

1.简介

JavaScript（简称“JS”）是一种具有函数优先的轻量级，解释型或即时编译型的编程语言。虽然它是作为开发 Web 页面的脚本语言而出名，但是它也被用到了很多非浏览器环境中，JavaScript 基于原型编程、多范式的动态脚本语言，并且支持面向对象、命令式、声明式、函数式编程范式。

二、JavaScript Attacks

1.low

我们点击提交，结果报错。

我们输入success，结果提示token不对。

源码

<?php
$page[ 'body' ] .= <<<EOF
<script>/*
MD5 code from here
https://github.com/blueimp/JavaScript-MD5
*/function rot13(inp) {return inp.replace(/[a-zA-Z]/g,function(c){return String.fromCharCode((c<="Z"?90:122)>=(c=c.charCodeAt(0)+13)?c:c-26);});}function generate_token() {var phrase = document.getElementById("phrase").value;document.getElementById("token").value = md5(rot13(phrase));}generate_token();
</script>
EOF;
?>

中间MD5的代码已经省去，查看源代码：发现phrase表示我们输入的内容，然后计算输入的token值document.getElementById("token").value = md5(rot13(phrase));

bp抓包

ChangeMe的

success的

我们发现输入的两次token值一样，在试验一个hhh，发现token还是一样的，猜测这个 token不是后台生成的，而是前台生成的。

F12打开控制台分别输入md5(rot13("ChangeMe")) ,md5(rot13("success"))查看，发现token值不一样。

我们在bp中把token的值改为在前端查到success的token值38581812b435834ebf84ebcc2c6424d6 phrase的值为success

Send一下发现Well donel 成功！

2.medium

源码

php

<?php
$page[ 'body' ] .= '<script src="' . DVWA_WEB_PAGE_TO_ROOT . 'vulnerabilities/javascript/source/medium.js"></script>';
?>

js(自己完善了一下）

function do_something(e){for(var t="",n=e.length-1;n>=0;n--)t+=e[n];return t}
setTimeout(function(){do_elsesomething("XX")
},300);
function do_elsesomething(e){//document.getElementById("token").value=do_something(e+document.getElementById("phrase").value+"XX")token=do_something(e+"success"+"XX")return token;
}
console.log(do_elsesomething("XX"));

查看源代码，发现引入了一个js来创建token
js代码中：**do_something(e)**的含义是将一个字符串翻转，就是倒过来
**setTimeout(function(){do_elsesomething(“XX”)},300)**的含义是每300毫秒执行一次do_elsesomething(“XX”)
**do_elsesomething(e)**的含义是该函数调运do_something（e）函数来设置token值，其中e等于XX+phrase+XX
总体含义是该函数通过将phrase进行字符串拼接，及XX+phrase+XX，最后将该值设置token及将XX+phrase+XX翻转倒过来即可。
XXsuccessXX -------> XXsseccusXX

js运行

bp抓包

我们发现token的值是XXChangeMeXX的倒序XXeMegnahCXX

使用success就是这样 XXsuccessXX -------> XXsseccusXX

3.high

<?php
$page[ 'body' ] .= '<script src="' . DVWA_WEB_PAGE_TO_ROOT . 'vulnerabilities/javascript/source/high.js"></script>';
?>

js代码经过混淆

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bp抓包好像没有什么可利用的。

使用http://deobfuscatejavascript.com解除混淆

生成 token 的步骤是：
1.由于有300毫秒延时，所以先执行了token_part_1(“ABCD”, 44)
2.然后再执行了 token_part_2(“XX”)
3.token_part_3被添加在提交按钮的click事件上，也就是点提交会触发执行。
在输入框输入 success 后，再到控制台输入token_part_1("ABCD", 44)和token_part_2("XX")这两个函数,最后点击按钮执行token_part_3()