Want to run this Docker container locally?

docker run -d -p 9080:80 --restart always --name dtmf-challenge joshbeck2024/ctf-dtmf-flag

Short Summary:

Decode the DTMF Tones
Convert Decimal Values to Ascii

Walkthrough

Start by inspecting the audio element ad the bottom of the page and downloading the file dtmf_flag.wav

These are DTMF tones:

• DTMF tones (Dual-Tone Multi-Frequency) are the sounds you hear when you press keys on a telephone keypad. Each key generates two tones at the same time—one low-frequency tone and one high-frequency tone—which together uniquely identify the pressed key.

Upload the file to this website:

<https://dtmf.netlify.app/>

It will decode the file and show you which keys were pressed:

Go ahead and replace the # with spaces using a notepad.

Decode from decimal to ASCII here.

• You should see the Flag!