freeBuf
主站

分类

漏洞 工具 极客 Web安全 系统安全 网络安全 无线安全 设备/客户端安全 数据安全 安全管理 企业安全 工控安全

特色

头条 人物志 活动 视频 观点 招聘 报告 资讯 区块链安全 标准与合规 容器安全 公开课

官方公众号企业安全新浪微博

FreeBuf.COM网络安全行业门户,每日发布专业的安全资讯、技术剖析。

FreeBuf+小程序

FreeBuf+小程序

记录第一次frida抓apk网络包 金币
2020-08-16 23:40:26

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.HttpURLConnectionImpl
com.android.okhttp.internal.http.HttpEngine
com.android.okhttp.internal.http.RetryableSink
com.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)

  1. 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
  2. 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");
    }
    };
  3. 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。

  1. 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
  2. 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 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);
    }
    }
  3. trace http相关class

    var traceAllHttpClass = function() {
    Java.perform(function() {
    Java.enumerateLoadedClasses({
    onMatch: function(name, handle) {
    /*"e.h.a.a$a",起初也拦截过app的该混淆类*/
    if (name.indexOf("com.android.okhttp.Http") != -1 || name.indexOf("com.android.okhttp.Request") != -1
    || name.indexOf("com.android.okhttp.internal") != -1) {
    traceClass(name);//对这三个class进行trace
    }
    },
    onComplete: function() {
    }
    });
    });
    };
  4. Request$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;
    }
  5. 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 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"}}

本文作者:, 转载请注明来自FreeBuf.COM

# Android # Frida # HTTPS劫持 # SSL证书
被以下专辑收录,发现更多精彩内容
+ 收入我的专辑
评论 按时间排序

登录/注册后在FreeBuf发布内容哦

相关推荐
  • 0 文章数
  • 0 评论数
  • 0 关注者
登录 / 注册后在FreeBuf发布内容哦
收入专辑