Frida Tutorial
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Install frida tools:
pip install frida-tools
pip install frida
Download and install in the android the frida server (Download the latest release).
One-liner to restart adb in root mode, connect to it, upload frida-server, give exec permissions and run it in backgroud:
adb root; adb connect localhost:6000; sleep 1; adb push frida-server /data/local/tmp/; adb shell "chmod 755 /data/local/tmp/frida-server"; adb shell "/data/local/tmp/frida-server &"
Check if it is working:
frida-ps -U #List packages and processes
frida-ps -U | grep -i <part_of_the_package_name> #Get all the package name
From: https://11x256.github.io/Frida-hooking-android-part-2/ (Parts 2, 3 & 4)
APKs and Source code: https://github.com/11x256/frida-android-examples
Follow the link to read it.
You can find some Awesome Frida scripts here: https://codeshare.frida.re/
Here you can find the more basic and interesting functionalities of Frida to make a quick script:
frida-ps -U
#Basic frida hooking
frida -l disableRoot.js -f owasp.mstg.uncrackable1
#Hooking before starting the app
frida -U --no-pause -l disableRoot.js -f owasp.mstg.uncrackable1
#The --no-pause and -f options allow the app to be spawned automatically,
#frozen so that the instrumentation can occur, and the automatically
#continue execution with our modified code.
import frida, sys
jscode = open(sys.argv[0]).read()
process = frida.get_usb_device().attach('infosecadventures.fridademo')
script = process.create_script(jscode)
print('[ * ] Running Frida Demo application')
script.load()
sys.stdin.read()
Hook the function
a() of the class sg.vantagepoint.a.cJava.perform(function () {
; rootcheck1.a.overload().implementation = function() {
rootcheck1.a.overload().implementation = function() {
send("sg.vantagepoint.a.c.a()Z Root check 1 HIT! su.exists()");
return false;
};
});
Hook java
exit()var sysexit = Java.use("java.lang.System");
sysexit.exit.overload("int").implementation = function(var_0) {
send("java.lang.System.exit(I)V // We avoid exiting the application :)");
};
Hook MainActivity
.onStart() & .onCreate()var mainactivity = Java.use("sg.vantagepoint.uncrackable1.MainActivity");
mainactivity.onStart.overload().implementation = function() {
send("MainActivity.onStart() HIT!!!");
var ret = this.onStart.overload().call(this);
};
mainactivity.onCreate.overload("android.os.Bundle").implementation = function(var_0) {
send("MainActivity.onCreate() HIT!!!");
var ret = this.onCreate.overload("android.os.Bundle").call(this,var_0);
};
Hook android
.onCreate() var activity = Java.use("android.app.Activity");
activity.onCreate.overload("android.os.Bundle").implementation = function(var_0) {
send("Activity HIT!!!");
var ret = this.onCreate.overload("android.os.Bundle").call(this,var_0);
};
Hooking a decryption function. Print the input, call the original function decrypt the input and finally, print the plain data:
function getString(data){
var ret = "";
for (var i=0; i < data.length; i++){
ret += data[i].toString();
}
return ret
}
var aes_decrypt = Java.use("sg.vantagepoint.a.a");
aes_decrypt.a.overload("[B","[B").implementation = function(var_0,var_1) {
send("sg.vantagepoint.a.a.a([B[B)[B doFinal(enc) // AES/ECB/PKCS7Padding");
send("Key : " + getString(var_0));
send("Encrypted : " + getString(var_1));
var ret = this.a.overload("[B","[B").call(this,var_0,var_1);
send("Decrypted : " + ret);
var flag = "";
for (var i=0; i < ret.length; i++){
flag += String.fromCharCode(ret[i]);
}
send("Decrypted flag: " + flag);
return ret; //[B
};
var string_class = Java.use("java.lang.String"); // get a JS wrapper for java's String class
my_class.fun.overload("java.lang.String").implementation = function(x){ //hooking the new function
var my_string = string_class.$new("My TeSt String#####"); //creating a new String by using `new` operator
console.log("Original arg: " +x );
var ret = this.fun(my_string); // calling the original function with the new String, and putting its return value in ret variable
console.log("Return value: "+ret);
return ret;
};
If you want to extract some attribute of a created object you can use this.
In this example you are going to see how to get the object of the class my_activity and how to call the function .secret() that will print a private attribute of the object:
Java.choose("com.example.a11x256.frida_test.my_activity" , {
onMatch : function(instance){ //This function will be called for every instance found by frida
console.log("Found instance: "+instance);
console.log("Result of secret func: " + instance.secret());
},
onComplete:function(){}
});
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- Do you work in a cybersecurity company? Do you want to see your company advertised in HackTricks? or do you want to have access to the latest version of the PEASS or download HackTricks in PDF? Check the SUBSCRIPTION PLANS!
Last modified 29d ago