Android hook方式抓包

Posted 2022-12-07 不会写代码的丝丽

前言

在跟大佬学习的时候发现另一种抓包方式，采用frida hook socket 字节流即可，哪里还需要管什么证书绑定，双向认证？

HTTP抓包原理

样本案例

class MainActivity : AppCompatActivity() 
    override fun onCreate(savedInstanceState: Bundle?) 
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById<Button>(R.id.btn).setOnClickListener 
            thread(name = "learnHttp") 
                val url = URL("http://www.baidu.com/")
                val urlConnection = url.openConnection() as HttpURLConnection
                try 
                    val ins: InputStream = BufferedInputStream(urlConnection.inputStream)
                    val readBytes = ins.readBytes()
                    Log.d("MainActivity", String(readBytes))
                    ins.close()
                 catch (e: java.lang.Exception) 
                    Log.e("MainActivity", "error", e);
                 finally 
                    urlConnection.disconnect()
                
            

        
    

我们分析HttpURLConnection如何发送网络请求才能明白一些hook点,这里使用android Studio自带的profiler。

当然上面分析比较多路径，这里采用别的方式分析，我们知道http会通过socket进行通信必然要通过socket输入输出流，然后断点获取输入流和输出流的地方即可。

可以看到最终返回的时java.net.SocketInputStream.

然后你只需要在下一个断点在这个类所有读取方法上

可以看到会走到其相关read

我们观察下这个字节数组数据方法

可以看到这个就是我们需要的相关数据，当然IDE显示的数据可能不是很正确。因为结构体body是被gzip压缩的。

所以我们这里使用frida hook这个类的读写函数即可。对http请求也如法复制即可。所以大佬根据上面的原理写出了如下的代码

//一个16进制打印工具
function jhexdump(array,off,len) 
    var ptr = Memory.alloc(array.length);
    for(var i = 0; i < array.length; ++i)
        Memory.writeS8(ptr.add(i), array[i]);
    //console.log(hexdump(ptr,  offset: off, length: len, header: false, ansi: false ));
    //console.log(hexdump(ptr,  offset: 0, length: array.length, header: false, ansi: false ));


function hook_socket()
    Java.perform(function()
        Java.use("java.net.SocketOutputStream").write.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.write(bytearry,int1,int2);
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            console.log("write bytearray contents=>\\r\\n", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            //console.log(jhexdump(bytearry));
            return result;
        
        

        Java.use("java.net.SocketInputStream").read.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.read(bytearry,int1,int2);
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            console.log("read bytearray contents=>\\r\\n", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            // console.log(jhexdump(bytearry));
            return result;
        

    )



function main()
	hook_socket()

setImmediate(main)

我们举例说明：

将上面的16进制拷贝到010editor

其中响应体被gzip压缩

我们把压缩内容内容保存的桌面取名httpcontent.gz

解压得到正确输出

HTTPS抓包原理

如法炮制断点输出流写入


如果无法关联源码可以请导入AOSP中extern/okhttp 源码(需要改包名等，内部使用jarjar.jar工具替换的)

com.android.org.conscrypt.ConscryptFileDescriptorSocket$SSLOutputStream

输入流同理

在Android10 上面的代码可能有变化

以下为大佬写的写的相关代码

function jhexdump(array,off,len) 
    var ptr = Memory.alloc(array.length);
    for(var i = 0; i < array.length; ++i)
        Memory.writeS8(ptr.add(i), array[i]);
    //console.log(hexdump(ptr,  offset: off, length: len, header: false, ansi: false ));
    //console.log(hexdump(ptr,  offset: 0, length: array.length, header: false, ansi: false ));


function hook_socket()
    Java.perform(function()
        console.log("hook_socket;")
        

        Java.use("java.net.SocketOutputStream").write.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.write(bytearry,int1,int2);
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            console.log("write bytearray contents=>\\r\\n", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            //console.log(jhexdump(bytearry));
            return result;
        
        

        Java.use("java.net.SocketInputStream").read.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.read(bytearry,int1,int2);
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            console.log("read bytearray contents=>\\r\\n", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            // console.log(jhexdump(bytearry));
            return result;
        

    )



function hook_SSLsocketandroid8()
    Java.perform(function()
        console.log("hook_SSLsocket")
        
        Java.use("com.android.org.conscrypt.ConscryptFileDescriptorSocket$SSLOutputStream").write.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.write(bytearry,int1,int2);
            //console.log("HTTPS write result,bytearry,int1,int2=>",result,bytearry,int1,int2)
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            console.log("bytearray contents=>", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            console.log(jhexdump(bytearry));
            return result;
        
        

        
        Java.use("com.android.org.conscrypt.ConscryptFileDescriptorSocket$SSLInputStream").read.overload('[B', 'int', 'int').implementation = function(bytearry,int1,int2)
            var result = this.read(bytearry,int1,int2);
            console.log("HTTPS read result,bytearry,int1,int2=>",result,bytearry,int1,int2)
            var ByteString = Java.use("com.android.okhttp.okio.ByteString");
            //console.log("bytearray contents=>", ByteString.of(bytearry).hex())
            //console.log(jhexdump(bytearry,int1,int2));
            //console.log(jhexdump(bytearry));
            return result;
        
        

    )



function hook_SSLsocket2android10()
    Java.perform(function()
        console.log(" hook_SSLsocket2")
        var ByteString = Java.use("com.android.okhttp.okio.ByteString");
        Java.use("com.android.org.conscrypt.NativeCrypto").SSL_write.implementation = function(long,NS,fd,NC,bytearray,int1,int2,int3)
            var result = this .SSL_write(long,NS,fd,NC,bytearray,int1,int2,int3);
            console.log("SSL_write(long,NS,fd,NC,bytearray,int1,int2,int3),result=>",long,NS,fd,NC,bytearray,int1,int2,int3,result)
            console.log(ByteString.of(bytearray).hex());
            return result;
        
        Java.use("com.android.org.conscrypt.NativeCrypto").SSL_read.implementation = function(long,NS,fd,NC,bytearray,int1,int2,int3)
            var result = this .SSL_read(long,NS,fd,NC,bytearray,int1,int2,int3);
            console.log("SSL_read(long,NS,fd,NC,bytearray,int1,int2,int3),result=>",long,NS,fd,NC,bytearray,int1,int2,int3,result)
            console.log(ByteString.of(bytearray).hex());
            return result;
              
    )


function main()
    console.log("Main")
   // hook_socket();
   hook_SSLsocketandroid8();
    //hook_SSLsocket2android10();

setImmediate(main)