hacktricks/mobile-apps-pentesting/android-app-pentesting/frida-tutorial/owaspuncrackable-1.md

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# Frida Tutorial 3
**From**: [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)
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## Solution 1 
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Based in [https://joshspicer.com/android-frida-1](https://joshspicer.com/android-frida-1) 
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**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
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Based in [https://joshspicer.com/android-frida-1](https://joshspicer.com/android-frida-1)&#x20;
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**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.");
});
```