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extensions

Problem

This is a really weird text file TXT? Can you find the flag?

Solution

  1. 1.
    A quick file type check with file reveals that we have a PNG file instead of a TXT file:
    file flag.txt
    flag.txt: PNG image data, 1697 x 608, 8-bit/color RGB, non-interlaced
  2. 2.
    Change the filename to flag.png and get the flag:
    Image with flag
  3. 3.
    Katana can solve this challenge:
    Target completed in 7.29 seconds after 6105 unit cases
    tesseract(/data/targets/flag.txt)
    picoCTF{now_you_know_about_extensions} - (copied)

Flag

picoCTF{now_you_know_about_extensions}