Reverse Engineering Write-up — SimpleS

Reverse Engineering Write-up — SimpleS

Challenge

The program displayed the message:

“Do something to get congratulations! I’m waiting…”

The goal was to make it print the Congratulations message.

Analysis

I opened the executable in a disassembler and checked the imported functions. The binary imported several Winsock functions such as socket(), bind(), listen(), and accept(), indicating that it was creating a TCP server.

While analyzing the code, I found that the program binds to 127.0.0.1 on port 31279 (0x7A2F) and then waits for an incoming connection using accept().

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After a successful connection, the program prints:

Congratulations!
Now write a little tutorial.

Solution

Enter 127.0.0.1:31279 in address bar of the borwser

After Entering, the program immediately displays the success message.

What I Learned

• Identify useful, imported functions.
• Recognize a simple TCP server from socket(), bind(), listen(), and accept().
• Convert hexadecimal values to ports (0x7A2F → 31279).
• Follow the execution flow to determine the success condition.