從系統的角度去尋找hook點,而不是為了抓包而抓包。
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(); } }
客戶端的重要程式碼在client.newCall()上,上面是okhttp官網的範例。從此處介面呼叫開始,終會呼叫至okhttp框架, okhttp本是sdk,後來aosp已經整合至系統,所以可以歸類至框架層。
框架層不詳述,主要就是這幾個java類別:
com.android.okhttp.internal.huc.HttpURLConnectionImpl com.android.okhttp.internal.http.HttpEngine com.android.okhttp.internal.http.RetryableSink com.android.okhttp.internal.http.CacheStrategy$Factory
其實client.newCall終會透過URL取得一個connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
這裡的urlConnection其實就是HttpURLConnectionImpl的實例,該類別有getInputStream getOutputStream方法,內部分別會呼叫HttpEngine的getBufferedRequestBody,getResponse。剛開始我嘗試hook過這兩個接口,例如hook getResponse後,可以將response印出來.
後來我發現,Request只能輸出header,無法輸出body。所以又埋頭繼續分析,getBufferedRequestBody這個函數剛好可以入手,取得一個sink,最後以RetryableSink為突破點,例如hook 其write函數就可以將body印出來。 write函數對應於app層面的urlConnection.getOutputStream().write。
後來發現一個Request,呼叫getBufferedReuqestBody函數可能不只一次,所以會有資料重複的問題,後來我又尋找到了CacheStrategy$Factory.get點進行Hook,發現還是有資料重複。發現以上hook都有弊端
資料重複
#非okhttp呼叫無法抓取
okhttp流程:sdk接口->okhttp框架->native(libc)2.分析過程中frida踩到的坑(重點都在註解中)
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
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.$new(); requestBody.writeTo(BufferObj); Logd(TAG, "\nrequest body :\n" + BufferObj.readString() + "\n"); } };
var printIntentAndExtras = function printIntentAndExtras(intentObj) { if (intentObj == null) return; var Intent = Java.use("android.content.Intent"); var Bundle = Java.use("android.os.Bundle"); var bundleObj = Intent.getExtras.call(intentObj); if (bundleObj != null) { Bundle.getSize.call(bundleObj, null);//调用getSize即可反序列化 } Logd(TAG, ‘printIntentAndExtras ’ + bundleObj); };
var URLHook = function() { var URL = Java.use('java.net.URL'); URL.openConnection.overload().implementation = function() { var retval = this.openConnection(); Logd('URL', openConnection' + retval); return retval; }; };//URL.openConnection调用概率比较大,但是不一定对网络进行请求
var jsonHook = function() { var xx = Java.use('e.h.a.a');//app smali var xxa_method = xx.a.overload('org.json.JSONObject', 'java.lang.String', 'java.lang.String'); xxa_method.implementation = function(jsonObj, str1, str2) { Logd("json", jsonObj + " str1: " + str1 + " str2" + str2); xxa_method.call(this, jsonObj, str1, str2); } }
var traceAllHttpClass = function() { Java.perform(function() { Java.enumerateLoadedClasses({ onMatch: function(name, handle) { /*"e.h.a.a$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() { } }); }); };
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; }
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); } });
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; };
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; } } } });即使直接強制verify返回true,仍然無法登錄,因為出現了相同的ssl問題錯誤。百度搜尋後找到了答案。 apktool解包,然後修改
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>
重打包簽名後運行一把,fiddle抓到了包,app也能正常登陸了,這次也是運氣好吧,app的ssl校驗只有單向app校驗,伺服器並沒有進行校驗。 四.結束從週二下午一直折騰到週五,最後從系統層面的HttpEngine尋找hook點並不是很好的方法,弊端也已明了。因此,在周日利用抓包工具和各種從百度找到的方法,逐步解決遇到的問題。 下面是抓到的兩個套件:
HTTP/1.1 200 OK
Date: Sun, 16 Aug 2020 06:27:34 GMT
Content-Type: application/json
Content-Length: 101
Connection: keep-alive
Grpc-Metadata-Content-Type: application/grpc
Vary: Origin
Vary: Accept-Encoding
{"result":{"errno":"OK","errmsg":"成功"},"data":{"version":"xxxxxxxx-351e-40cf-aaa9-3177d6df9b7f"}}
-----------------------------------
HTTP/1.1 200 OK
Date: Sun, 16 Aug 2020 06:27:34 GMT
Content-Type: application/json
Content-Length: 99
Connection: keep-alive
Grpc-Metadata-Content-Type: application/grpc
Vary: Origin
Vary: Accept-Encoding
{"result":{"errno":"OK","errmsg":"成功"},"data":{"nodeToken":"xxxxxxxc24d79f55c0b07beaf50cb566"}}
POST https://tap-xxxxxxx.xxxxxx.com/api/v2/Android/analytics/basic HTTP/1.1
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cjbcjdsabcjvbXVCJ9.eyJ1aWQiOjE4ODMzMDEsInNlY3JldCI6IjAzNzE0M2Y3LTExMTUtNGY2Yi1iNzQxLWUyMjc5ZDM3MGY3MCIsImV4cCI6MTU5NzgxNjQ0MiwiaXNzIjoiZ3Vlc3QgbG9naW4ifQ.W3SiO0-afbhxPITjRinnhyWhZLy1bzZhYexm5VCWklI
X-Device-ID: 9xxxxxxx84d4542e
X-Loc: ["China","Shanghai","Shanghai","","ChinaUnicom","31.224349","121.4767528","Asia/Shanghai","UTC+8","310000","86","CN","AP","xxx.166.xxx.xxx"]
X-App-Version: 2.2.0
Content-Type: application/json; charset=utf-8
Content-Length: 208
Host: xx-xxxx.xxxxxx.com
Connection: Keep-Alive
Accept-Encoding: gzip
User-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 OK
Date: Sun, 16 Aug 2020 06:27:35 GMT
Content-Type: application/json
Content-Length: 43
Connection: keep-alive
Grpc-Metadata-Content-Type: application/grpc
Vary: Origin
Vary: Accept-Encoding
{"result":{"errno":"OK","errmsg":"成功"}}
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