AUDIO STEGANOGRAPHY CHALLENGE
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File: suspicious_audio.wav

This audio file was found on a suspect's device during a forensic
investigation. Our analysis suggests it may contain a hidden message.

The audio sounds like a normal tone, but something is hidden inside.

Tools and techniques to investigate:
  Audacity - open the file, analyze waveform visually
  Python with wave module - read sample values
  Look at the Least Significant Bits (LSB) of audio samples
  The message is encoded 1 bit per sample, 8 samples per character
  MSB first within each byte

Python starter code:
  import wave, struct
  with wave.open('suspicious_audio.wav', 'r') as wav:
      frames = wav.readframes(wav.getnframes())
      samples = struct.unpack('<' + 'h' * (len(frames)//2), frames)
      bits = [s & 1 for s in samples[:400]]
      chars = []
      for i in range(0, len(bits), 8):
          byte_bits = bits[i:i+8]
          if len(byte_bits) == 8:
              c = chr(sum(b << (7-j) for j, b in enumerate(byte_bits)))
              if c == '\x00': break
              chars.append(c)
      print(''.join(chars))

Flag format: PlainlySec{...}
