猿人学— 第一届第1题（解题思路附源码）

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猿人学 — 第1届第1题（解题思路附源码）

• F12进入开发者工具—> 发现停止在debugger处 —> 右键点击Never pause here后下一步
  
  
• 翻页，抓包后发现请求携带page和m两个参数，page应该就是页数，m则需要逆向
  
  
• 依次查找文件，寻找m在哪里被赋值，随后在VM14235：6中发现混淆代码比较可疑
  • 进入文件，给request函数中的赋值语句给上断点，重新请求
  • 发现'\x6d'='m'，而_0x5d83a3['\x6d']的值则与Payload中m的值神似
  • 继续调试，让请求过去，验证，发现Payload中m确实与此处的值对应

    

• 手动翻译一下代码

  var _0x2268f9 = Date['parse'](new Date()) +  var _0x57feae = ooΘ0Θ(_0x2268f9['toString'()])+window['f']; const _0x5d83a3 = { 
       }; _0x5d83a3['page'] = window['page'] _0x5d83a3['m'] = _0x57feaa + '丨'+ _0x2268f9 / 1000; 

• 逆向m，则必须知道_0x57feaa和_0x2268f9，而_0x2268f9很明显是一个时间戳，因此主要解决_0x57feaa
  • 多次请求后发现ooΘ0Θ(_0x2268f9['toString'()])返回一个空字符串，因此主要关注window['f']
  • 通过Console面板定义Hook，定位window['f']在哪里被赋值

    Object.defineProperty(window, 'f', { 
            set: function(val) { 
            console.log('f的值:', val); debugger return val; } } ) 

    

  • 再次请求，停止后，向上寻找调用栈，发现是一个hex_md5函数的返回值，而这个函数的形参则是之前的_0x2268f9，即时间戳，不过注意类型是字符串（我开始没有注意，导致得到的m一直是一个错误的固定值）

    

• 最后就是去扣hex_md5函数及其运行依赖放到node中执行（当然也可以将整个js文件copy下来），源码如下

  window = global var hexcase = 0; var chrsz = 16; function hex_md5(a) { 
        return binl2hex(core_md5(str2binl(a), a.length * chrsz)) } function core_md5(p, k) { 
        p[k >> 5] |= 128 << ((k) % 32); p[(((k + 64) >>> 9) << 4) + 14] = k; var o = ; var n = -; var m = -; var l = ; for (var g = 0; g < p.length; g += 16) { 
        var j = o; var h = n; var f = m; var e = l; o = md5_ff(o, n, m, l, p[g + 0], 7, -); l = md5_ff(l, o, n, m, p[g + 1], 12, -); m = md5_ff(m, l, o, n, p[g + 2], 17, ); n = md5_ff(n, m, l, o, p[g + 3], 22, -); o = md5_ff(o, n, m, l, p[g + 4], 7, -); l = md5_ff(l, o, n, m, p[g + 5], 12, ); m = md5_ff(m, l, o, n, p[g + 6], 17, -); n = md5_ff(n, m, l, o, p[g + 7], 22, -); o = md5_ff(o, n, m, l, p[g + 8], 7, ); l = md5_ff(l, o, n, m, p[g + 9], 12, -); m = md5_ff(m, l, o, n, p[g + 10], 17, -42063); n = md5_ff(n, m, l, o, p[g + 11], 22, -); o = md5_ff(o, n, m, l, p[g + 12], 7, ); l = md5_ff(l, o, n, m, p[g + 13], 12, -); m = md5_ff(m, l, o, n, p[g + 14], 17, -); n = md5_ff(n, m, l, o, p[g + 15], 22, ); o = md5_gg(o, n, m, l, p[g + 1], 5, -); l = md5_gg(l, o, n, m, p[g + 6], 9, -); m = md5_gg(m, l, o, n, p[g + 11], 14, ); n = md5_gg(n, m, l, o, p[g + 0], 20, -); o = md5_gg(o, n, m, l, p[g + 5], 5, -); l = md5_gg(l, o, n, m, p[g + 10], 9, ); m = md5_gg(m, l, o, n, p[g + 15], 14, -); n = md5_gg(n, m, l, o, p[g + 4], 20, -); o = md5_gg(o, n, m, l, p[g + 9], 5, ); l = md5_gg(l, o, n, m, p[g + 14], 9, -); m = md5_gg(m, l, o, n, p[g + 3], 14, -); n = md5_gg(n, m, l, o, p[g + 8], 20, ); o = md5_gg(o, n, m, l, p[g + 13], 5, -); l = md5_gg(l, o, n, m, p[g + 2], 9, -); m = md5_gg(m, l, o, n, p[g + 7], 14, ); n = md5_gg(n, m, l, o, p[g + 12], 20, -); o = md5_hh(o, n, m, l, p[g + 5], 4, -); l = md5_hh(l, o, n, m, p[g + 8], 11, -); m = md5_hh(m, l, o, n, p[g + 11], 16, ); n = md5_hh(n, m, l, o, p[g + 14], 23, -); o = md5_hh(o, n, m, l, p[g + 1], 4, -); l = md5_hh(l, o, n, m, p[g + 4], 11, ); m = md5_hh(m, l, o, n, p[g + 7], 16, -); n = md5_hh(n, m, l, o, p[g + 10], 23, -); o = md5_hh(o, n, m, l, p[g + 13], 4, ); l = md5_hh(l, o, n, m, p[g + 0], 11, -); m = md5_hh(m, l, o, n, p[g + 3], 16, -); n = md5_hh(n, m, l, o, p[g + 6], 23, ); o = md5_hh(o, n, m, l, p[g + 9], 4, -); l = md5_hh(l, o, n, m, p[g + 12], 11, -); m = md5_hh(m, l, o, n, p[g + 15], 16, ); n = md5_hh(n, m, l, o, p[g + 2], 23, -); o = md5_ii(o, n, m, l, p[g + 0], 6, -); l = md5_ii(l, o, n, m, p[g + 7], 10, ); m = md5_ii(m, l, o, n, p[g + 14], 15, -); n = md5_ii(n, m, l, o, p[g + 5], 21, -); o = md5_ii(o, n, m, l, p[g + 12], 6, ); l = md5_ii(l, o, n, m, p[g + 3], 10, -); m = md5_ii(m, l, o, n, p[g + 10], 15, -); n = md5_ii(n, m, l, o, p[g + 1], 21, -); o = md5_ii(o, n, m, l, p[g + 8], 6, ); l = md5_ii(l, o, n, m, p[g + 15], 10, -); m = md5_ii(m, l, o, n, p[g + 6], 15, -); n = md5_ii(n, m, l, o, p[g + 13], 21, ); o = md5_ii(o, n, m, l, p[g + 4], 6, -); l = md5_ii(l, o, n, m, p[g + 11], 10, -); m = md5_ii(m, l, o, n, p[g + 2], 15, ); n = md5_ii(n, m, l, o, p[g + 9], 21, -); o = safe_add(o, j); n = safe_add(n, h); m = safe_add(m, f); l = safe_add(l, e) } return Array(o, n, m, l) } function md5_cmn(h, e, d, c, g, f) { 
        return safe_add(bit_rol(safe_add(safe_add(e, h), safe_add(c, f)), g), d) } function md5_ff(g, f, k, j, e, i, h) { 
        return md5_cmn((f & k) | ((~f) & j), g, f, e, i, h) } function md5_gg(g, f, k, j, e, i, h) { 
        return md5_cmn((f & j) | (k & (~j)), g, f, e, i, h) } function md5_hh(g, f, k, j, e, i, h) { 
        return md5_cmn(f ^ k ^ j, g, f, e, i, h) } function md5_ii(g, f, k, j, e, i, h) { 
        return md5_cmn(k ^ (f | (~j)), g, f, e, i, h) } function safe_add(a, d) { 
        var c = (a & 65535) + (d & 65535); var b = (a >> 16) + (d >> 16) + (c >> 16); return (b << 16) | (c & 65535) } function bit_rol(a, b) { 
        return (a << b) | (a >>> (32 - b)) } function str2binl(d) { 
        var c = Array(); var a = (1 << chrsz) - 1; for (var b = 0; b < d.length * chrsz; b += chrsz) { 
        c[b >> 5] |= (d.charCodeAt(b / chrsz) & a) << (b % 32) } return c } function binl2hex(c) { 
        var b = hexcase ? "0ABCDEF" : "0abcdef"; var d = ""; for (var a = 0; a < c.length * 4; a++) { 
        d += b.charAt((c[a >> 2] >> ((a % 4) * 8 + 4)) & 15) + b.charAt((c[a >> 2] >> ((a % 4) * 8)) & 15) } return d } function playload_m(){ 
        var _0x2268f9 = Date['parse'](new Date()) + () return hex_md5(_0x2268f9.toString()) + '丨' + _0x2268f9 / (1000); } 

  import requests import execjs # 请求获取页面数据 def get_data(page, m): res = requests.get( url='https://match.yuanrenxue.cn/api/match/1', params={ 
        'page': page, 'm': m } ) return res # 执行js代码获得参数m def get_m(): with open('v1.js', 'rt', encoding='utf-8') as f: js_string = f.read() js_code = execjs.compile(js_string) param_m = js_code.call('playload_m') return param_m # 处理请求返回的数据，计算机票平均价格 def get_average(page): count = 0 value = 0 param_m = get_m() for pid in range(1, page + 1): url_res = get_data(pid,param_m) if url_res.status_code == 200: page_data = get_data(pid,param_m).json()['data'] for item in page_data: value += int(item['value']) count += len(page_data) else: print(f"{ 
         pid}页数据请求失败:{ 
         url_res.json()}") print(f"前{ 
         page}页机票平均价格:{ 
         value / count}") if __name__ == '__main__': get_average(5) 

• 运行结果

  

• 笔者为刚接触逆向的小白，若上面有错误、不合理和值得优化的地方，欢迎各位大佬批评指正！