25 lines
1.3 KiB
Markdown
25 lines
1.3 KiB
Markdown
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## Difficulty
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Easy
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## Category
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Reverse Engineering
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## How To Solve
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When you run the app on an android device/emulator, you see that you are not a nice person. You will need to reverse engineer the APK to discover the flag.
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This time, you can use [JADX](https://github.com/skylot/jadx) to analyze the APK. After performing `jadx oats2.apk`, you will be able to navigate to a file named `MainActivityKt.java` located somewhere under `sources/`. The following function provides you with the flag when you are nice:
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```java
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public static final void Greeting$showFlag(MutableState<String> mutableState, boolean isNice) {
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if (isNice) {
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int num2 = 42 + 58;
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int num3 = (num2 * 42) + num2;
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String[] array = {"zefiluhfz", "nelsqefvon", "maqzpeiuvfbqddela", "vcnbdqiyfub", "camw33pus", "woohvfdowinoo", "oiuyqecqer", "lusg9876hdfskj", "igc", "tf"};
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String fContent = array[8] + array[9] + '{' + array[num3 % array.length] + array[(num3 * num2) % array.length];
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String flag = fContent + '}';
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mutableState.setValue(flag);
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return;
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}
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mutableState.setValue("NOPE");
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}
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```
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In order to obtain the flag, you can either modify and recompile entire source code, or simply copy, compile and execute only the function itself.
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## Flag
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`igctf{zefiluhfzzefiluhfz}`
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