Matryoshka doll


Matryoshka dolls are a set of wooden dolls of decreasing size placed one inside another. What's the final one? Image: this


  1. 1.
    The problem suggests files places inside of other files, so let's run binwalk dolls.jpg.
    0 0x0 PNG image, 594 x 1104, 8-bit/color RGBA, non-interlaced
    3226 0xC9A TIFF image data, big-endian, offset of first image directory: 8
    272492 0x4286C Zip archive data, at least v2.0 to extract, compressed size: 378956, uncompressed size: 383938, name: base_images/2_c.jpg
    651614 0x9F15E End of Zip archive, footer length: 22
    Sure enough, there are several files.
  2. 2.
    We can extract the files by running binwalk --dd='.*' dolls.jpg and then cd _dolls.jpg.extracted.
  3. 3.
    After some trial and error, the correct solution is to extract the zip file, cd base_images, and then repeat step 3 on 2_c.jpg.
  4. 4.
    Now that you are in _2_c.jpg.extracted, extract the zip file and repeat step 3.
  5. 5.
    Repeat the above steps of extracting and binwalking until you end up at this path: _dolls.jpg.extracted/base_images/_2_c.jpg.extracted/base_images/_3_c.jpg.extracted/base_images/_4_c.jpg.extracted/136DA-(1). There is a flag.txt file in this directory that contains the flag.