Depixelating information in the document (finding what was not supposed to be found)

In short

• While playing the GreenHorn box on Hack The Box, I encountered a situation where a PDF contained a pixelated password

  • https://www.hackthebox.com/achievement/machine/409699/617

• Upon deeper investigation, I found ways to depixelate the image

  • with

    • https://github.com/spipm/Depix

• the result

• potential password

sidefromsidetheothersidesidefromsidetheotherside

Diving deeper

• I will dive deeper into how it works another day

• Today, I'll focus on how to depixelate the image

• I extracted the image from the PDF. (Note: Do not take a screenshot! Always extract the image directly from the PDF to preserve quality.)

  • I initially made the mistake of thinking it would be fine to use a screenshot.

  • As a result, Depix was unable to depixelate the image

• After I passed it to Depix

python3 depix.py -p pix.png -s ./images/searchimages/debruinseq_notepad_Windows10_closeAndSpaced.png -o output.png

• the result from

• to

References

• https://github.com/spipm/Depix