mirror of
https://github.com/carlospolop/hacktricks
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216 lines
7.2 KiB
Markdown
216 lines
7.2 KiB
Markdown
# Frida Tutorial 2
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**From**: [https://11x256.github.io/Frida-hooking-android-part-2/](https://11x256.github.io/Frida-hooking-android-part-2/) \(Parts 2, 3 & 4\)
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**APKs and Source code**: [https://github.com/11x256/frida-android-examples](https://github.com/11x256/frida-android-examples)
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The part 1 is so easy.
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**Some parts of the original code doesn't work and have been modified here.**
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## Part 2
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Here you can see an example of how to **hook 2 functions with the same name** but different parameters.
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Also, you are going to learn how to **call a function with your own parameters**.
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And finally, there is an example of how to **find an instance of a class and make it call a function**.
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```javascript
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//s2.js
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console.log("Script loaded successfully ");
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Java.perform(function x() {
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console.log("Inside java perform function");
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var my_class = Java.use("com.example.a11x256.frida_test.my_activity");
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//Hook "fun" with parameters (int, int)
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my_class.fun.overload("int", "int").implementation = function (x, y) { //hooking the old function
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console.log("original call: fun(" + x + ", " + y + ")");
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var ret_value = this.fun(2, 5);
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return ret_value;
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};
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//Hook "fun" with paramater(String)
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var string_class = Java.use("java.lang.String");
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my_class.fun.overload("java.lang.String").implementation = function (x) { //hooking the new function
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console.log("*")
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//Create a new String and call the function with your input.
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var my_string = string_class.$new("My TeSt String#####");
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console.log("Original arg: " + x);
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var ret = this.fun(my_string);
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console.log("Return value: " + ret);
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console.log("*")
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return ret;
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};
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//Find an instance of the class and call "secret" function.
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Java.choose("com.example.a11x256.frida_test.my_activity", {
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onMatch: function (instance) {
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console.log(tring, and the it has"Found instance: " + instance);
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console.log("Result of secret func: " + instance.secret());
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},
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onComplete: function () { }
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});
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});
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```
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You can see that to create a String first is has referenced the class _java.lang.String_ and then it has created a _$new_ object of that class with a String as content. This is the correct way to create a new object of a class. But, in this case, you could just pass to `this.fun()` any String like: `this.fun("hey there!")`
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### Python
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```python
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//loader.py
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import frida
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import time
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device = frida.get_usb_device()
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pid = device.spawn(["com.example.a11x256.frida_test"])
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device.resume(pid)
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time.sleep(1) #Without it Java.perform silently fails
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session = device.attach(pid)
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script = session.create_script(open("s2.js").read())
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script.load()
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#prevent the python script from terminating
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raw_input()
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```
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```text
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python loader.py
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```
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## Part 3
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### Python
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Now you are going to see how to send commands to the hooked app via Python to call function:
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```python
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//loader.py
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import time
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import frida
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def my_message_handler(message, payload):
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print message
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print payload
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device = frida.get_usb_device()
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pid = device.spawn(["com.example.a11x256.frida_test"])
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device.resume(pid)
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time.sleep(1) # Without it Java.perform silently fails
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session = device.attach(pid)
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with open("s3.js") as f:
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script = session.create_script(f.read())
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script.on("message", my_message_handler)
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script.load()
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command = ""
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while 1 == 1:
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command = raw_input("Enter command:\n1: Exit\n2: Call secret function\n3: Hook Secret\nchoice:")
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if command == "1":
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break
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elif command == "2":
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script.exports.callsecretfunction()
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elif command == "3":
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script.exports.hooksecretfunction()
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```
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The command "**1**" will **exit**, the command "**2**" will find and **instance of the class and call the private function** _**secret\(\)**_ and command "**3**" will **hook** the function _**secret\(\)**_ so it **return** a **different string**.
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The, if you call "**2**" you will get the **real secret**, but if you call "**3**" and then "**2**" you will get the **fake secret**.
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### JS
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```javascript
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console.log("Script loaded successfully ");
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var instances_array = [];
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function callSecretFun() {
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Java.perform(function () {
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if (instances_array.length == 0) { // if array is empty
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Java.choose("com.example.a11x256.frida_test.my_activity", {
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onMatch: function (instance) {
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console.log("Found instance: " + instance);
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instances_array.push(instance)
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console.log("Result of secret func: " + instance.secret());
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},
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onComplete: function () { }
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});
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}
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else {//else if the array has some values
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console.log("Result of secret func: " + instances_array[0].secret());
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}
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});
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}
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function hookSecret() {
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Java.perform(function () {
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var my_class = Java.use("com.example.a11x256.frida_test.my_activity");
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var string_class = Java.use("java.lang.String");
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my_class.secret.overload().implementation = function(){
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var my_string = string_class.$new("TE ENGANNNNEEE");
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return my_string;
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}
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});
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}
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rpc.exports = {
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callsecretfunction: callSecretFun,
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hooksecretfunction: hookSecret
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};
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```
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## Part 4
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Here you will see how to make **Python and JS interact** using JSONs objects. JS use the `send()` function to send data to the python cliente, and Python uses `post()` functions to send data to ths JS script. The **JS will block the execution** until is receives s response from Python.
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### Python
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```python
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//loader.py
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import time
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import frida
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def my_message_handler(message, payload):
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print message
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print payload
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if message["type"] == "send":
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print message["payload"]
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data = message["payload"].split(":")[1].strip()
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print 'message:', message
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data = data.decode("base64")
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user, pw = data.split(":")
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data = ("admin" + ":" + pw).encode("base64")
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print "encoded data:", data
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script.post({"my_data": data}) # send JSON object
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print "Modified data sent"
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device = frida.get_usb_device()
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pid = device.spawn(["com.example.a11x256.frida_test"])
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device.resume(pid)
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time.sleep(1)
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session = device.attach(pid)
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with open("s4.js") as f:
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script = session.create_script(f.read())
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script.on("message", my_message_handler) # register the message handler
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script.load()
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raw_input()
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```
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### JS
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```javascript
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console.log("Script loaded successfully ");
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Java.perform(function () {
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var tv_class = Java.use("android.widget.TextView");
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tv_class.setText.overload('java.lang.CharSequence').implementation = function (x) {
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var string_to_send = x.toString();
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var string_to_recv = "";
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send(string_to_send); // send data to python code
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recv(function (received_json_object) {
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string_to_recv = received_json_object.my_data;
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}).wait(); //block execution till the message is received
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console.log("Final string_to_recv: "+ string_to_recv)
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return this.setText(string_to_recv);
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}
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});
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```
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There is a part 5 that I am not going to explain because there isn't anything new. But if you want to read it is here: [https://11x256.github.io/Frida-hooking-android-part-5/](https://11x256.github.io/Frida-hooking-android-part-5/)
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