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Steganography and PNGs
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Brian de Heus
October 12, 2019
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Steganography and PNGs
How to hide arbitrary data in PNGs and have image CDNs host it for you.
Brian de Heus
October 12, 2019
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Transcript
Free Unlimited Storage With This One Weird Trick! System Administrators
Hate Him!
steganography /stɛɡəˈnɒɡrəfɪ/ noun 1. the practice of concealing messages or
information within other non-secret text or data.
Herodotus
Admiral Jeremiah Denton
Message Under The Stamp
Brian de Heus briandotjp
Append After End Byte +
Binary Storage
Least Significant Bit Source: https://www.peerlyst.com/posts/the-threat-of-digital-steganography-cloaked-malware-to-u-s-critical-infrastructure-systems-ian-barwise-m-s-cissp-ceh-cnda
None
PNG Portable Network Graphics
None
signature 8 bytes chunk size 4 bytes chunk type 4
bytes chunk data n bytes chunk crc 4 bytes chunk size 4 bytes chunk type 4 bytes chunk data n bytes chunk crc 4 bytes chunk size 4 bytes chunk type 4 bytes chunk data n bytes chunk crc 4 bytes
Critical Chunks IHDR PLTE* IDAT IEND
Ancillary Chunks bKGD cHRM dSIG eXIf gAMA hIST iCCP iTXt
pHYs sBIT sPLT sRGB sTER tEXt tIME tRNS zTXt
criticality scope reserved safety CRITICAL non-critical PUBLIC private ALWAYS UPPERCASE
DON’T COPY safe to copy
I H D R CRITICAL PUBLIC DON’T COPY
e X I f non-critical PUBLIC safe to copy
None
Make my own chunks!
p u N k non-critical private safe to copy
None
+
Chunk size: 13 Chunk type: IHDR CRC: 9a768270 Chunk size:
218087 Chunk type: IDAT CRC: e11d26bc Chunk size: 0 Chunk type: IEND CRC: ae426082 Hiding 27 kB ( 28208 bytes) Injecting punk chunk Punk chunk injected Reached EOF
Chunk size: 13 Chunk type: IHDR CRC: 9a768270 Chunk size:
218087 Chunk type: IDAT CRC: e11d26bc Chunk size: 28208 Chunk type: puNk CRC: 8cccb594 Chunk size: 0 Chunk type: IEND Reached EOF
http://i.imgur.com/Qk5BP19.png
Demo Time!
Lesson 1 Do not trust user input
Lesson 2 Do not trust anyone
Lesson 3 Doge meme isn’t dead wow much brave such
opinion
Thanks!!