# Frida Tutorial 3

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***

**This is a summary of the post**: [https://joshspicer.com/android-frida-1](https://joshspicer.com/android-frida-1)\
**APK**: [https://github.com/OWASP/owasp-mstg/blob/master/Crackmes/Android/Level\_01/UnCrackable-Level1.apk](https://github.com/OWASP/owasp-mstg/blob/master/Crackmes/Android/Level_01/UnCrackable-Level1.apk)

## Solution 1

Based in [https://joshspicer.com/android-frida-1](https://joshspicer.com/android-frida-1)

**Hook the \_exit()**\_ function and **decrypt function** so it print the flag in frida console when you press verify:

```javascript
Java.perform(function () {
  send("Starting hooks OWASP uncrackable1...");

  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 : " + getString(ret));

    var flag = "";
    for (var i=0; i < ret.length; i++){
      flag += String.fromCharCode(ret[i]);
    }
    send("Decrypted flag: " + flag);
    return ret; //[B
  };

  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  :)");
  };

  send("Hooks installed.");
});
```

## Solution 2

Based in [https://joshspicer.com/android-frida-1](https://joshspicer.com/android-frida-1)

**Hook rootchecks** and decrypt function so it print the flag in frida console when you press verify:

```javascript
Java.perform(function () {
  send("Starting hooks OWASP uncrackable1...");

  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 : " + getString(ret));

    var flag = "";
    for (var i=0; i < ret.length; i++){
      flag += String.fromCharCode(ret[i]);
    }
    send("Decrypted flag: " + flag);
    return ret; //[B
  };

  var rootcheck1 = Java.use("sg.vantagepoint.a.c");
  rootcheck1.a.overload().implementation = function() {
    send("sg.vantagepoint.a.c.a()Z   Root check 1 HIT!  su.exists()");
    return false;
  };

  var rootcheck2 = Java.use("sg.vantagepoint.a.c");
  rootcheck2.b.overload().implementation = function() {
    send("sg.vantagepoint.a.c.b()Z  Root check 2 HIT!  test-keys");
    return false;
  };

  var rootcheck3 = Java.use("sg.vantagepoint.a.c");
  rootcheck3.c.overload().implementation = function() {
    send("sg.vantagepoint.a.c.c()Z  Root check 3 HIT!  Root packages");
    return false;
  };

  var debugcheck = Java.use("sg.vantagepoint.a.b");
  debugcheck.a.overload("android.content.Context").implementation = function(var_0) {
    send("sg.vantagepoint.a.b.a(Landroid/content/Context;)Z  Debug check HIT! ");
    return false;
  };

  send("Hooks installed.");
});
```

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{% hint style="success" %}
Learn & practice AWS Hacking:<img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-ce8af1068db7be4ad9003f8ddb02fea8f943f1a4%2Farte.png?alt=media" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-ce8af1068db7be4ad9003f8ddb02fea8f943f1a4%2Farte.png?alt=media" alt="" data-size="line">\
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<summary>Support HackTricks</summary>

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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks_live)**.**
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