一个神奇的JS混淆，JSFuck!

JSFuck，整体由6个字符[, ], (, ), !, +组成，但却是可以正常运行的JS代码，JSFuck程序可以在任何Web浏览器或引擎中运行解释JavaScript！

看一段代码，源代码为：document.write('FuckJS');

看着很牛逼的样子，但是它有个很致命的缺点，就是太长……看下图行数↓

一句document.write('FuckJS');用JSFuck编写的话代码能达到惊人的1000+行36474个字符。

但是，如果从渗透测试人员的角度想呢？这样混淆的话是不是大多过滤都过滤不掉了？所以JSFuck还可用于绕过网站上提交的恶意代码的检测，例如跨站点脚本（XSS）攻击。

一些简单的JS语句还是比较短的，比如alert(1)

<script type="text/javascript">
			[][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!+[]]]
			[([][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]] + [])[!+[] + !+[] + !+[]] + (!![] + [][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]])[+!+[] + [+[]]] + ([][
				[]
			] + [])[+!+[]] + (![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[+!+[]] + ([][
				[]
			] + [])[+[]] + ([][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+[]] + (!![] + [][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]])[+!+[] + [+[]]] + (!![] + [])[+!+[]]]((![] + [])[+!+[]] + (![] + [])[!+[] + !+[]] + (!![] + [])[!+[] + !+[] +
				!+[]] + (!![] + [])[+!+[]] + (!![] + [])[+[]] + (![] + [][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]])[!+[] + !+[] + [+[]]] + [+!+[]] + (!![] + [][(![] + [])[+[]] + ([![]] + [][
				[]
			])[+!+[] + [+[]]] + (![] + [])[!+[] + !+[]] + (!![] + [])[+[]] + (!![] + [])[!+[] + !+[] + !+[]] + (!![] + [])[+!
				+[]]])[!+[] + !+[] + [+[]]])()
</script>

所以还是有两大优点的

1、脚本注入时防止过滤

2、一定程度加密关键代码（生成代码很长，不适合加密大量代码。只能一定程度上加密，不能依赖）

感兴趣的可以看一下维基百科：https://en.wikipedia.org/wiki/JSFuck

或者JSFuck的Github：https://github.com/aemkei/jsfuck

还有JSFuck的官网：http://www.jsfuck.com/

反混淆的话可以借鉴一下这篇文章：https://www.jianshu.com/p/1dc99e3d927c