frida如何抓apk网络包 • Worktile社区

一 . 埋头分析踩坑路

从系统的角度去寻找hook点，而不是为了抓包而抓包。

1.okhttp调用流程

public static final MediaType JSON= MediaType.get("application/json; charset=utf-8");OkHttpClient client = new OkHttpClient();String post(String url, String json) throws IOException {RequestBody body = RequestBody.create(json, JSON);Request request = new Request.Builder().url(url).post(body).build();try (Response response = client.newCall(request).execute()) {return response.body().string();}}

上面是okhttp官网的一个demo，关键代码就在client.newCall。从此处接口调用开始，终会调用至okhttp框架, okhttp本是sdk，后来aosp已经集成至系统，所以可以归类至框架层。

框架层不详述，主要就是这几个java类:

com.android.okhttp.internal.huc.HttpURLConnectionImplcom.android.okhttp.internal.http.HttpEnginecom.android.okhttp.internal.http.RetryableSinkcom.android.okhttp.internal.http.CacheStrategy$Factory

其实client.newCall终会通过URL获取一个connection

HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

这里的urlConnection其实就是HttpURLConnectionImpl的实例，该类有getInputStream getOutputStream方法，内部分别会调用HttpEngine的getBufferedRequestBody，getResponse。刚开始我尝试hook过这两个接口，比如hook getResponse后，可以将response打印出来.

之后我发现Request只能打印header，并不能打印body。所以又埋头继续分析，getBufferedRequestBody这个函数刚好可以入手，获取一个sink，最后以RetryableSink为突破点，比如hook 其write函数就可以将body打印出来。write函数对应于app层面的urlConnection.getOutputStream().write。

后来发现一个Request,调用getBufferedReuqestBody函数可能不止一次，所以会有数据重复的问题，后来我又寻找到了CacheStrategy$Factory.get点进行Hook，发现还是有数据重复。发现以上hook均有弊端

数据重复
非okhttp调用无法抓取

接着又继续从native层的send,sendmsg,write,recv,read打印调用栈。最后折腾了三天，决定放弃治疗，还是采取工具吧。

okhttp流程：sdk接口->okhttp框架->native(libc)

2.分析过程中frida踩到的坑(重点都在注释中)

android.util.Log不打印

var Logd = function Logd(tag, msg) {Java.use("android.util.Log").d(tag, msg);};Logd('http-body-', '11111111111111');//该log不打印Logd('http-body', '11111111111111');//该log打印

匿名内部类获取成员需要反射

var printRequest = function(request) {var Buffer = Java.use("com.android.okhttp.okio.Buffer");var bodyField = request.getClass().getDeclaredField('body');bodyField.setAccessible(true);if (request == null) return;Logd('http', 'printRequest: request' + request);//var requestBody = request.body();//gadget直接报错var requestBody = bodyField.get(request);var requestBodyClass = requestBody.getClass();var ClassInstanceArray = Java.array('java.lang.Class', []);//var contentLengthMethod = requestBodyClass.getMethod("contentLength");//gadget直接报错var contentLengthMethod = requestBodyClass.getMethod("contentLength", ClassInstanceArray);contentLengthMethod.setAccessible(true);var ObjectInstanceArray = Java.array('java.lang.Object', []);var contentLength = requestBody ? contentLengthMethod.invoke(requestBody, ObjectInstanceArray) : 0;//if (contentLength == 0) contentLength = contentLen;Logd('http', 'printRequest contentLength: ' + contentLength);if (contentLength > 0) {var BufferObj = Buffer.$new();requestBody.writeTo(BufferObj);Logd(TAG, "\nrequest body :\n" + BufferObj.readString() + "\n");}};

android.os.Bundle打印，需要将Bundle unparcel

var printIntentAndExtras = function printIntentAndExtras(intentObj) {if (intentObj == null) return;var Intent = Java.use("android.content.Intent");var Bundle = Java.use("android.os.Bundle");var bundleObj = Intent.getExtras.call(intentObj);if (bundleObj != null) {Bundle.getSize.call(bundleObj, null);//调用getSize即可反序列化}Logd(TAG, ‘printIntentAndExtras ’ + bundleObj);};

踩到的坑其实不只上面的，刚开始也百度过一些frida网络拦截的方案，还仔细的研究了okhttp的Interceptor方案，最后发现app也是用了拦截器，所以就发生冲突，导致无法使用该方案。

也纯粹的分析过app的smali，寻找调用栈以及网络请求，最后，只有几个比较小的收获，可能对读者没有用处，不过记录一下，方便自己以后回忆。

java.net.URL拦截

var URLHook = function() {var URL = Java.use('java.net.URL');URL.openConnection.overload().implementation = function() {var retval = this.openConnection();Logd('URL', openConnection' + retval);return retval;};};//URL.openConnection调用概率比较大，但是不一定对网络进行请求

拦截app调用http请求前使用json的地方，这只是其中之一

var jsonHook = function() {var xx = Java.use('e.h.a.a');//app smalivar xxa_method = xx.a.overload('org.json.JSONObject', 'java.lang.String', 'java.lang.String');xxa_method.implementation = function(jsonObj, str1, str2) {Logd("json", jsonObj + " str1: " + str1 + " str2" + str2);xxa_method.call(this, jsonObj, str1, str2);}}

trace http相关class

var traceAllHttpClass = function() {Java.perform(function() {Java.enumerateLoadedClasses({onMatch: function(name, handle) {/*"e.h.a.a$a",起初也拦截过app的该混淆类*/if (name.indexOf("com.android.okhttp.Http") != -1 || name.indexOf("com.android.okhttp.Request") != -1|| name.indexOf("com.android.okhttp.internal") != -1) {traceClass(name);//对这三个class进行trace}},onComplete: function() {}});});};

Request$Builder拦截

var BuilderClass = Java.use('com.android.okhttp.Request$Builder')BuilderClass.build.implementation = function () {//LOG('com.android.okhttp.HttpUrl$Builder.build overload', { c: Color.Light.Cyan });//printBacktrace();var retval = this.build();Logd(TAG, "retval:" + retval);printRequest(retval);return retval;}

property_get拦截

var nativePropertyGetAddr = Module.findExportByName(null, '__system_property_get');Interceptor.attach(nativePropertyGetAddr, {onEnter: function onEnter(args) {this._name = args[0].readCString();this._value = args[1];},onLeave: function onLeave(retval) {if (this._name.indexOf("ro.build.id") != -1) {var virtualDevice = getVirtualDevice();if (DEBUG_PROP) Logd(TAG, "__system_property_get fake " + this._name + "=>to " + virtualDevice.build_id);this._value.writeUtf8String(virtualDevice.build_id);}var strFilter = /^ro\./g;if (DEBUG_PROP && this._name.match(strFilter) != null) Logd(TAG, "__system_property_get " + this._name);}});

二 . 设备android_id导致用户过期的处理

var DEBUG_PROP = false;var DEVICE_CONFIG = "/sdcard/.device";function getVirtualDevice() {var nativeOpen = new NativeFunction(Module.findExportByName(‘libc.so’, 'open'), 'int', ['pointer', 'int']);var nativeRead = new NativeFunction(Module.findExportByName('libc.so', 'read'), 'int', ['int', 'pointer', 'int']);var fd = nativeOpen(Memory.allocUtf8String(DEVICE_CONFIG), 0);var mem = Memory.alloc(1024);var readLen = nativeRead(fd, mem, 1024);var json = JSON.parse(mem.readCString(readLen));return json;}Secure.getString.implementation = function () {var retval = this.getString(arguments[0], arguments[1]);if (DEBUG_PROP) Logd(TAG, "Settings.Secure get " + arguments[1] + " val " + retval);if (arguments[1].indexOf("android_id") != -1) {var virtualDevice = getVirtualDevice();return virtualDevice.android_id;}return retval;};

三 . 使用抓包工具fiddle抓包脱坑

1.fiddle代理设置OK，app却无法登陆

分析adb log,进程有 java.security.cert.CertPathValidatorException的打印，之前也看过一些frida拦截抓包绕过证书的帖子。先试一把暴力搜索：

Java.perform(function(){const groups = Java.enumerateMethods('*!verify/u');var classes = null;for(var i in groups){var classes = groups[i]['classes'];for(var i in classes){Java.use(classes[i]['name']).verify.overload('java.lang.String', 'javax.net.ssl.SSLSession').implementation = function() {printBacktrace();LOG("[+] invoke verify", { c: Color.Red });return true;}}}});

调用verify直接暴力返回true，依然无法登陆，报错是同样的ssl问题。百度搜索后找到了答案。apktool解包，然后修改

res/xml/network_security_config.xml<?xml version="1.0" encoding="utf-8"?><network-security-config><base-config cleartextTrafficPermitted="true"><trust-anchors><certificates src="system" /><!--添加fiddle证书可信任<certificates src="user" />--></trust-anchors></base-config></network-security-config>

重打包签名后运行一把，fiddle抓到了包，app也能正常登陆了，这次也是运气好吧，app的ssl校验只有单向app校验，服务器并没有进行校验。

四.结束

从周二下午一直折腾到周五，最后从系统层面的HttpEngine寻找hook点并不是很好的方法，弊端也已明了。所以趁着周日的时间，再试一下各种百度到的方法—-抓包工具，然后一步步将遇到的问题pass掉。

下面是抓到的两个包：

HTTP/1.1 200 OKDate: Sun, 16 Aug 2020 06:27:34 GMTContent-Type: application/jsonContent-Length: 101Connection: keep-aliveGrpc-Metadata-Content-Type: application/grpcVary: OriginVary: Accept-Encoding{"result":{"errno":"OK","errmsg":"成功"},"data":{"version":"xxxxxxxx-351e-40cf-aaa9-3177d6df9b7f"}}-----------------------------------HTTP/1.1 200 OKDate: Sun, 16 Aug 2020 06:27:34 GMTContent-Type: application/jsonContent-Length: 99Connection: keep-aliveGrpc-Metadata-Content-Type: application/grpcVary: OriginVary: Accept-Encoding{"result":{"errno":"OK","errmsg":"成功"},"data":{"nodeToken":"xxxxxxxc24d79f55c0b07beaf50cb566"}}

POST https://tap-xxxxxxx.xxxxxx.com/api/v2/Android/analytics/basic HTTP/1.1Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cjbcjdsabcjvbXVCJ9.eyJ1aWQiOjE4ODMzMDEsInNlY3JldCI6IjAzNzE0M2Y3LTExMTUtNGY2Yi1iNzQxLWUyMjc5ZDM3MGY3MCIsImV4cCI6MTU5NzgxNjQ0MiwiaXNzIjoiZ3Vlc3QgbG9naW4ifQ.W3SiO0-afbhxPITjRinnhyWhZLy1bzZhYexm5VCWklIX-Device-ID: 9xxxxxxx84d4542eX-Loc: ["China","Shanghai","Shanghai","","ChinaUnicom","31.224349","121.4767528","Asia/Shanghai","UTC+8","310000","86","CN","AP","xxx.166.xxx.xxx"]X-App-Version: 2.2.0Content-Type: application/json; charset=utf-8Content-Length: 208Host: xx-xxxx.xxxxxx.comConnection: Keep-AliveAccept-Encoding: gzipUser-Agent: okhttp/4.7.2{"deviceID":"9xxxxxxx84d4542e","model":"V1813BA","systemVersion":"9","version":"2.2.0","location":{"latitude":xx.x99x990990991,"longitude":xxx.26689769073256},"network":{"g2":0,"g3":0,"g4":4,"g5":0,"wifi":4}}-----------------------------------HTTP/1.1 200 OKDate: Sun, 16 Aug 2020 06:27:35 GMTContent-Type: application/jsonContent-Length: 43Connection: keep-aliveGrpc-Metadata-Content-Type: application/grpcVary: OriginVary: Accept-Encoding{"result":{"errno":"OK","errmsg":"成功"}}

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文章标题：frida如何抓apk网络包，发布者：亿速云，转载请注明出处：https://worktile.com/kb/p/23847