The Game

Introduction

The Game is a reverse-engineering / binary analysis challenge. The premise: a cipher hid critical secrets inside a Tetris binary. The goal is to analyze the supplied binary, extract the embedded data, and decode it to reveal the flag or secret.

Files in the downloaded ZIP

$ unzip Tetris____.zip (the file name may vary for different users)

As you can see in the image provided above we have Tetrix.exe to examine for the hidden flag.

Recon: basic file checks

Before deep analysis, run basic checks so you know the type and permissions of the binary.

- Check file type
    $ file Tetrix.exe
- Check file permissions
    $ ls -l Tetrix.exe

About the strings tool

strings extracts sequences of printable characters from binary files. It's handy in reverse-engineering because flags, URLs, error messages and other plaintext artifacts are often embedded in executables or resources. Typical behavior and useful options:

• default extracts ASCII printable runs (commonly minimum length 4).

• -n N (or --bytes=N) sets the minimum match length to N (useful to avoid short noisy fragments).

• -a scans the entire file.

• -t prints offsets (useful to locate the string in the binary). strings is part of GNU binutils and available on most Linux systems. For Unicode/UTF-16 data or exotic encodings, combine strings with other tools (or try different strings flags / a disassembler) to ensure you catch non-ASCII payloads.

Immediate solution

Run:

strings -n 6 Tetris.exe | grep -i "thm{"

Explanation:

• strings -n 6 only shows printable runs of length ≥ 6 (reduces noise and surfaces longer tokens like flags).

• grep -i "thm{" filters case-insensitively for the flag prefix thm{}. The matching line printed by this pipeline should contain the flag.