The Challenge

A PNG file is given. The flag is not in the image visually, not in EXIF data, and not in any metadata field. It is literally concatenated as plain text somewhere inside the raw bytes of the file.

Approach

If a flag string appears verbatim in a binary file you can find it with str.find on the raw file content. Reading the entire file in binary mode returns a bytes object; calling .find("flag".encode()) returns the offset. Everything from that offset onwards is the flag until the terminal }.

No image library needed — this is a raw byte scan.

Solution

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with open("flag.png", "rb") as flag:
    text = flag.read()
    index = text.find("flag".encode())
    for i in range(index, len(text)):
        print(chr(text[i]), end="")

text.find("flag".encode()) locates the start. The loop prints characters in order from that byte onwards — the flag ends with } so the terminal character is visible in stdout.

What I Learned

Before analysing an image with any library, running strings or doing a raw find for known patterns is always the first pass. Files carrying hidden ASCII content often carry it verbatim — no encoding, no encryption. file.read() then .find() is the fastest possible approach.