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前言

一篇酷狗app安卓逆向的文章，难度适中。
样本: 酷狗app v10.8.8
工具: jadx、Pixel3 安卓10、frida、charles
小伙伴可以跟着一起做做

提示：以下是本篇文章正文内容，下面案例可供参考

一、抓包待分析参数

1.1 charles抓包-音乐评论接口

可以看到signature参数，用apipost模拟请求下试试

1.2 模拟请求

1.3 查壳

二、分析

2.1 packageName

package=“com.kugou.android” 接下来hook需要用到

2.2 搜索关键词

hashMap.put(“signature”,com.kugou.android.ads.feev4.a.a(sb.toString())); 相当可疑了 我们点进去看下

代码如下

    public static Map<String, Object> a(Context context, JSONObject jSONObject) {
        HashMap hashMap = new HashMap();
        hashMap.put("dfid", com.kugou.common.q.b.a().dq());
        hashMap.put("appid", com.kugou.android.b.c.d());
        hashMap.put("mid", br.j(context));
        hashMap.put("uuid", com.kugou.common.q.b.a().ak());
        hashMap.put("clientver", Integer.valueOf(d.a(context)));
        hashMap.put("clienttime", Long.valueOf(System.currentTimeMillis() / 1000));
        String a2 = com.kugou.android.ads.feev4.a.a(hashMap);
        StringBuilder sb = new StringBuilder();
        sb.append(a2);
        sb.append(jSONObject == null ? "" : jSONObject.toString());
        hashMap.put("signature", com.kugou.android.ads.feev4.a.a(sb.toString()));
        return hashMap;
    }

可以看到定义hashMap put(“dfid”) put(“appid”)等等

String a2 = com.kugou.android.ads.feev4.a.a(hashMap);
StringBuilder.append(a2),

hook下a2的值

2.3 a2追踪hook

com.kugou.android.ads.feev4.a.a(hashMap);

jadx代码如下：

  public static String a(Map<String, Object> map) {
        if (map == null || map.isEmpty()) {
            return "";
        }
        ArrayList<String> arrayList = new ArrayList(map.keySet());
        Collections.sort(arrayList);
        StringBuilder sb = new StringBuilder();
        for (String str : arrayList) {
            if (!TextUtils.isEmpty(str)) {
                sb.append(str);
                sb.append(ContainerUtils.KEY_VALUE_DELIMITER);
                sb.append(map.get(str));
            }
        }
        return sb.toString();
    }

参数 --> [object Object]
参数 --> appid=1005clienttime=秒级时间戳clientver=10889dfid=xxmid=xxuuid=xx

hook代码如下：

import frida, sys

def on_message(message, data):
    if message['type'] == 'send':
        print("[*] {0}".format(message['payload']))
    else:
        print(message)
        
jscode_hook = """
    Java.perform(
        function(){
			var a2_class = Java.use("com.kugou.android.ads.feev4.a")
            a2_class.a.overload('java.util.Map').implementation = function (m) {
			       console.log("参数 --> "+m)
			       var result = this.a(m)
			       console.log("参数 --> "+result1)
			       return result
			    }
 })
"""
process = frida.get_usb_device().attach('com.kugou.android')
script = process.create_script(jscode_hook)
script.on('message', on_message)
print('[*] Hook Start Running')
script.load()
sys.stdin.read()

a2 = "appid=1005clienttime=秒级时间戳clientver=10889dfid=xxmid=xxuuid=xx"

接着往下分析 hashMap.put(“signature”, com.kugou.android.ads.feev4.a.a(sb.toString()));点进去看下a()

2.4 b2追踪hook

String b2 = h.a().b(a.AbstractC1142a.N);

返回了b2的值 hook看看

b2 = “OIlwieks28dk2k092lksi2UIkp”

return ba.c(b2 + str + b2);

2.5 hook 加密函数

hook代码如下:

import frida, sys

def on_message(message, data):
    if message['type'] == 'send':
        print("[*] {0}".format(message['payload']))
    else:
        print(message)


jscode_hook = """
Java.perform(
    function(){
            var sign_class = Java.use("com.kugou.common.utils.ba");
            console.log(sign_class);
            if (sign_class != undefined) {
                    sign_class.b.overload('java.lang.String').implementation = function (str) {
                    console.log("参数: ==> : " + str);
                    var res = sign_class.b(str);
                    console.log("解密结果: ==> " + res);
                    return res;
                }
            }
    }
)
"""

process = frida.get_usb_device().attach('com.kugou.android')
script = process.create_script(jscode_hook)
script.on('message', on_message)
print('[*] Hook Start Running')
script.load()
sys.stdin.read()

hook结果:

params: OIlwieks28dk2k092lksi2UIkpappid=1005clienttime=1643368936clientver=10889dfid=1bHOPF2BFRqk3UpxUx1hzf53mid=232539908206342312896345662088253784255uuid=ed42ee74c48dd921427f2729a68787a7{“plat”:0,“channel”:“287”,“operator”:7,“networktype”:2,“userid”:0,“vip_type”:65530,“m_type”:0,“tags”:"{}",“device”:{“phonebrand”:“google”,“sysmodel”:“Pixel%203”,“osversion”:“10”,“boot_time”:“ae3d80cd-0450-415a-ab64-814b54c1dd6e”,“os_update_time”:“441644.63333339”,“width”:1080,“height”:2028},“song”:{“hash”:“ce388811b08b3327c388e2b0ed1f2d30”,“albumid”:0,“album_audio_id”:339101224},“mode”:“normal”}OIlwieks28dk2k092lksi2UIkp
结果: ca66b35e1581e9494f52cbec986816eb 32位 试下是不是md5

运气很好signature是参数进行拼接处理后的md5结果

总结

大家感兴趣的可以跟着做下
代码就不放了准备过年啦
祝小伙伴们虎年虎虎生威