JS逆向|非常实用的扣代码教程来了，欢迎收藏

痛定思痛。 2022-12-19 03:44 108阅读 0赞

声明：本文只作学习研究，禁止用于非法用途，否则后果自负，如有侵权，请告知删除，谢谢！

经过简单的分析，已知某网站参数的加密位置在这里:

![format_png][]

在控制台下输入f()并回车:

![format_png 1][]

跟进该函数后，在第一行打上断点:

![format_png 2][]

按下快捷键F8，停在此处:

![format_png 3][]

单步执行，来到这行:

![format_png 4][]

代码 var n = r.wordsToBytes(s(t, e));调用了两个函数，分别是r.wordsToBytes 和 s,在控制台看看t,e的值:

![format_png 5][]

t是上面讲到的固定的实参，e则未定义，不用理会，因此我们先将s函数扣出来看看,按照上面的方法，控制台输入s并回车跟进，来到这里:

![format_png 6][]

一直到这里，都是与s相关的代码:

![format_png 7][]

因此，将这段代码扣出来,保存到文件(我这里命名为md5.js),注意去掉**s前面的括号**以及:

![format_png 8][]

保存以后，构造一个实参，并调用s函数:

![format_png 9][]

直接在node下面跑一下，看看报啥错:

![format_png 10][]

提示这里的o未定义，那跟进代码里面看看o是怎么定义的:

![format_png 11][]

分析代码不难得知，这里实际是调用了o.stringToBytes这个函数，控制台输入看看:

![format_png 12][]

双击跟进，来到这里:

![format_png 13][]

直接把这个 n 对象扣出来，加入到s函数代码中，然后在照着逻辑加入这么一行代码:

![format_png 14][]

再次运行，看结果:

![format_png 15][]

再次报错，r未定义，按照之前的方法，跟进到r相关的代码在这里:

![format_png 16][]

发现此时又定义了一个n，是base64的码表，因此按照上面的方式进入s函数肯定是不行的，因为变量名的污染，也导致的代码的臃肿，我这里以返回值的形式赋值，代码如下:

再次运行，有结果了:

![format_png 17][]

回到浏览器，看看这个s函数的值是否正确:

![format_png 18][]

控制台输入s(t,e):

![format_png 19][]

扣到这里，再分析函数r.wordsToBytes，发现居然就是刚才扣的r对象，这下就省事多了，直接比对结果吧:

![format_png 20][]

在扣出来的代码上添加输出即可:

console.log(r.wordsToBytes(s(tmp)));

运行看结果:

![format_png 21][]

与上面的结果也是惊人的一致。

回到浏览器，看这里return的是啥:

![format_png 22][]

这是一个三目表达式，直接在浏览器上看看逻辑：

![format_png 23][]

可以看到，最终执行了r.bytesToHex(n)，在扣出来的代码上添加输出:

console.log(r.bytesToHex(r.wordsToBytes(s(tmp))));

![format_png 24][]

可以看到，结果出来了。

至此，代码抠取完毕。至于怎么给Python调用，请参考之前的两篇文章。

[format_png]: /images/20221120/b8ad420a727c45e794af32b26cd77694.png
[format_png 1]: /images/20221120/7f6897807e1a4b1bad569d66d3db734d.png
[format_png 2]: /images/20221120/5d993cae51244094a44c66b78da2e545.png
[format_png 3]: /images/20221120/acef69cf18254adda6d1053000a1b520.png
[format_png 4]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHdvOVljUmdpYVMzSWZCVW5YNHBzMU5FOEJJTFl3VXc5UUxaOWJyUjUyUmlheGlhVGlhZGljaWNpYjZGSHcvNjQw?x-oss-process=image/format,png
[format_png 5]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MDVDdTRhdExhTHVjWk1kSW5kSG42M1kxUzVWNkEyb25pYWljY1RoMTZpYlhrSGFIOGYyb3hHbU9ZQS82NDA?x-oss-process=image/format,png
[format_png 6]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHlWT2UxZ0h5b1pFREgzWTIzMHZpY3BUTnFkbDBPVjZRem90UHBnYjRNNWNYbHZJZ1F6UUxVbVEvNjQw?x-oss-process=image/format,png
[format_png 7]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MDg2czhuMmo4bVBKSTVETEdUQUtsaWJmM2ljMlJWYkx2VVZCMkJCMGJrd1UyNUJhTFFlb3RRNEFnLzY0MA?x-oss-process=image/format,png
[format_png 8]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MGljWTk0d3REUkZGd3kzRm1PdEptWDVkU3lBYUM5Z0I0NzRiR1lkTkU0Vkg1azh6cTVRWUdDemcvNjQw?x-oss-process=image/format,png
[format_png 9]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHhkMzBPcVBpYzRuWUx2b2lhcm10d3lma0F6RUpQcG5uSmxKSWxLMndCQXUzVXIxWENkaFMxcnB3LzY0MA?x-oss-process=image/format,png
[format_png 10]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHl1Uldwc1VUOG9DbHhiaWFWemJtc21uRzRqZzJuSGZEWFZaOWN1SGFXWG9PU1hhMlJYRHQydlEvNjQw?x-oss-process=image/format,png
[format_png 11]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MFR6ejlhZkdlbThiSlRMbU1zNzd5OHlSTlhEM3NiYmppYjRBS3dSaWJjYkdyZlljd1d4RUdRSXdnLzY0MA?x-oss-process=image/format,png
[format_png 12]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHVBcWt6SkxxZE1MVEFnN1NPaWFpYWNBWE5Hd2Y3MjQwaWIyVTl0MklIdWExRFg5aWM1VmNRY2lidEtRLzY0MA?x-oss-process=image/format,png
[format_png 13]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MGRLQUJUTzVkU1IzWHR2aWJEMGVwNVY3Q2lhS0MyaWJISGRsWjdOajNLV21ndGJjeVY0YVJtdjhYQS82NDA?x-oss-process=image/format,png
[format_png 14]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MEtmaWIwQko1VmJOUXh0RWpZaFFqUkFYaDFoWUpwbkxVR2hSaWM5ZFlIeTNCa2ZDYWJNeXl4RGhRLzY0MA?x-oss-process=image/format,png
[format_png 15]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHBwYW12MTdpYkw0S0xpY0NzUDQ5R0RKUkJyd1E0UVpwQmliV1IxdWs2ZFNodzBpY2lhb2t3dzhpY3ZPZy82NDA?x-oss-process=image/format,png
[format_png 16]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MExOaWJ1THdOaWNlM0FMS0dmV2lhaWFrMlpNQWs0SUgyUFFpYkNBeWFiNUQ0NHZHOGVTZE1pY01EeHBVdy82NDA?x-oss-process=image/format,png
[format_png 17]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MGZKTjE0bHdkMDFoS1dsY2UxWnZvYUtydlZ1bDc1cTZBeUVIUkRBWmljZGlhdm9Xbms2ZmFsTFdnLzY0MA?x-oss-process=image/format,png
[format_png 18]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MENYaWNsUmpCVG50TkE2Y3I2NUZYRzZNcmZjblhEY3NRaWNja0hER2RrMlU2SnM5bzlWSXFpYklVUS82NDA?x-oss-process=image/format,png
[format_png 19]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094ME5wZmt2dmR3aDlkT05EUG5jeGp1ZGliUWthWUU4bExjMU1XWHlTdW9XVDN0ZWp5Qnh2b3puVmcvNjQw?x-oss-process=image/format,png
[format_png 20]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MEhJemljY0duVGFhOWljQ3NuQlNrblhJbDNSNm45TVFXWmt6b3RkWTFmMFBvc3lsbklBcThLS2N3LzY0MA?x-oss-process=image/format,png
[format_png 21]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MGVlUE12YkVsU2hCRDZweUxTcEZ1aEFmdEdhajAycWljOTJiZXlGQnNyb3hjZUdTbjdOa014UGcvNjQw?x-oss-process=image/format,png
[format_png 22]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHIwWlJpYVhxTXJpYjduOWhUSTQ3VXhnZUxRV3l0ZWF2aWIwc25xeDRFWno3M0w2cmN0clREU20wZy82NDA?x-oss-process=image/format,png
[format_png 23]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MHh5c1BkaWE5NkRzamljeGVRQnYxWEN6MFdRdHBRRmlhakV1THZ6cnZRaWE0MnoyZTM4Sld4czgzTmcvNjQw?x-oss-process=image/format,png
[format_png 24]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X3BuZy9MbGw4dHgwTURSMUlUMUJZMzhidTI0alQzNnJSS094MGJsUm9pY3NFSWliQ2hnRzM5YkZsUlNISzBQaWJVOXp0TkNKdjF4WVFhMUFrOEQ5OWhuTDBFaWFkUGcvNjQw?x-oss-process=image/format,png