知识点： DES加密,重写加密函数

解题思路

请求查看结果地址，发现是结果加密

进入调试

打断点,发现是crypto-js加密

利用控制台查看变量值

既然知道了crypto-js加密

var k = P('crypto-js')
  , C = X
  , q = k['enc']['Utf8']['parse'](C)
  , v = k['AES']['decrypt'](l, q, {
    'mode': k['mode']['ECB'],
    'padding': k['pad']['Pkcs7']

编写js代码

const CryptoJS = require("crypto-js");

function I(X, l) {
    var k = CryptoJS
        , C = X
        , q = k['enc']['Utf8']['parse'](C)
        , v = k.AES.decrypt(l, q, {
        'mode': k['mode']['ECB'],
        'padding': k['pad']['Pkcs7']
    });
    return v['toString'](k['enc']['Utf8']);
}

X = "lVyahWFq";
L = "ohKADHk8zYXczliObcRsvE70kmTI2RiN94ZOxQgxbhQ7pueMCCcH7mnDZU2Tj2KwP0cqYgzsflRzt/Qls+efrZtGFaLomQw24v9FvIOso6lMYKrKtw5qP3b8d13G1tQXIuHILMMXDSrtUjX3vV+nUl7lV8KebHccY0STT0un12bMkODx2FTcv93sn2UHoBMTIWBM3CY+cQpOYEYB7iovImwasNLA5vsYxgntDuyxubvP5oi7FZPvHqtThy3gw9ivk+MyCBpW21Gr2aF/Wz/BHA10B5alDqSzP0cqYgzsflQCxHiUkgI+FptGFaLomQw2T1hUihgNUvLYnFuUWRJ6sw==";

console.log(I(X, L));

执行发现，报错

Error: Malformed UTF-8 data

猜是魔改过的CryptoJS,下面进行单步调试

控制台打印q

本地打印，输出值相同，没有问题

继续调试

控制台打印v

本地打印，输出值不相同

经过多次调试，发现是 k.AES.decrypt 存在魔改

v = k.AES.decrypt(l, q, {
        'mode': k['mode']['ECB'],
        'padding': k['pad']['Pkcs7']
    }

应该是DES重写了AES函数，

k.DES.decrypt