安卓逆向 - Frida Hook（抓包实践）

一、引言

上篇文章：安卓逆向 - 基础入门教程_小馒头yy的博客-CSDN博客介绍了Frida的安装、基本使用，今天我们来看看Frida常用Hook和基于Frida抓包实践。

二、Frida常用 Hook脚本

1、hook java.net.URL

function hook1() {
    var URL = Java.use('java.net.URL');
    URL.$init.overload('java.lang.String').implementation = function (a) {
        console.log('加密前：' + a)
        showStacks()
        this.$init(a)
    }
}

2、hook okhttp3 HttpUrl

function hookOkhttp3() {
    var Builder = Java.use('okhttp3.Request$Builder');
    Builder.url.overload('okhttp3.HttpUrl').implementation = function (a) {
        console.log('a: ' + a)
        var res = this.url(a);
        showStacks()
        console.log("res: " + res)
        return res;
    }
}

3、hook okhttp3 addHeader

function hook() {
    var Builder = Java.use("okhttp3.Request$Builder");
    Builder["addHeader"].implementation = function (str, str2) {
        console.log("key: " + str)
        console.log("val: " + str2)
        showStacks()
        var result = this["addHeader"](str, str2);
        console.log("result: " + result);
        return result;
    };
}

4、打印堆栈

function showStacks() {
    Java.perform(function () {
        console.log(Java.use("android.util.Log").getStackTraceString(Java.use("java.lang.Exception").$new()));
    });
}

5、hook Base64

function hookBase() {
    // Base64
    var Base64Class = Java.use("android.util.Base64");
    Base64Class.encodeToString.overload("[B", "int").implementation = function (a, b) {
        var rc = this.encodeToString(a, b);
        console.log(">>> Base64 " + rc);
        return rc;
    }
}

6、hook HashMap

function hookMap() {
    var Build = Java.use("java.util.HashMap");
    Build["put"].implementation = function (key, val) {
        console.log("key : " + key)
        console.log("val : " + val)
        return this.put(key, val)
    }
}

三、某麦网抓包实践

本篇以某麦网帖子详情接口，演示如何基于Frida hook抓包

1、安装某麦网8.*.*.apk

2、搭建Frida hook 环境，注入 hook java.net.URL脚本

3、点进帖子详情打印出如下堆栈，我们可以根据打印出的信息，跟栈分析该接口的请求头。

https://acs.m.taobao.com/gw/mtop.damai.wireless.discovery.detail.get/1.4/?source=10101&version=6000168&type=originaljson&data=%7B%22contentId%22%3A%2211088650%22%2C%22appType%22%3A%221%22%2C%22source%22%3A%2210101%22%2C%22osType%22%3A%222%22%2C%22pageSize%22%3A%2230%22%2C%22pageIndex%22%3A%221%22%2C%22version%22%3A%226000168%22%2C%22channel_from%22%3A%22damai_market%22%7D&appType=1&osType=2&channel_from=damai_market
java.lang.Exception
        at java.net.URL.<init>(Native Method)
        at tb.yy0.m(Taobao:1)
        at anet.channel.request.a.p(Taobao:2)
        at anet.channel.session.TnetSpdySession.w(Taobao:18)
        at anetwork.channel.unified.NetworkTask.sendRequest(Taobao:6)
        at anetwork.channel.unified.NetworkTask.run(Taobao:44)
        at anetwork.channel.unified.UnifiedRequestTask$a.proceed(Taobao:15)
        at com.taobao.orange.sync.NetworkInterceptor.intercept(Taobao:30)
        at anetwork.channel.unified.UnifiedRequestTask$a.proceed(Taobao:7)
        at anetwork.channel.unified.UnifiedRequestTask$3.run(Taobao:2)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:428)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:761)

4、使用Jadx打开某麦网apk

从at tb.yy0.m(Taobao:1)跟栈分析

根据调用栈往上走，定位到如下位置，注意这行代码：

ALog.f("awcn.TnetSpdySession", "", aVar.n(), "request headers", aVar.g());

代码注释很清楚了 request headers，我们跟进 hook aVar.g() 这个方法

public Map<String, String> g() {
        return Collections.unmodifiableMap(this.f);
    }

hook之，对象输出可以使用 JSONObject转一下

 var JSONObject = Java.use("com.alibaba.fastjson.JSONObject");

function hook6() {
    var JSONObject = Java.use("com.alibaba.fastjson.JSONObject");
    var a = Java.use("anet.channel.request.a");
    a["g"].implementation = function () {
        var result = this["g"]();
        console.log("result : " + JSONObject.toJSON(result).toString());
        return result;
    };
}

打印出如下内容：