write-ups-challenges-2024-2025/oats1/SOLUTION.md

Difficulty

Easy

Category

Reverse Engineering

How To Solve

When you run the app on an android device/emulator, you immediately notice that you won't find the flag in the app itself.

Instead, you need to use a tool like apktool to reverse engineer the APK file. Running apktool d oats1.apk will decode the file. Grep "IGCTF" in the obtained folder to discover the flag.

> grep -r "IGCTF" .
./smali_classes3/com/example/oats/MainActivityKt.smali:    const-string v14, "IGCTF{Unus3d_vari4bl3}"

Flag

IGCTF{Unus3d_vari4bl3}