Ouija

Platform: HackTheBox | Category: Reversing | Difficulty: Medium | Author: D3v0o0Nu11 | Date: 2026-02-10

Description

You've made contact with a spirit from beyond the grave! Unfortunately, they speak in an ancient tongue of flags, so you can't understand a word. You've enlisted a medium who can translate it, but they like to take their time...

Solution Approach

Core idea: Identify the weakness from source review or fingerprinting first. Iterate with incremental payloads instead of guessing.

Steps

1. First, unzip the .zip file given, then jump to the extracted directory.

2. Check the file type.

3. It's not stripped. Hence it's easier for us to reverse the binary.

4. Let us run the binary in GDB.

5. It stucks here (?)

6. Let us decompile the binary using ghidra and open the main() function.

7. Got the reason why the program took long enough to output a message.

8. Well change every sleep() function's that say 10 to 0.

9. Export the binary, make it executeable, now run the binary.

10. As you can see, it starts to print out the flag.

Flag

REDACTED

Lessons Learned

1. Identify the weakness from source review or fingerprinting first.
2. Iterate with incremental payloads instead of guessing.
3. Reuse the same pattern in future engagements.