# CTF Recap #1 --- ## Welcome  ---- ### Tools used: * **file** * classify file * **exiftool** * read metadata * **binwalk** * analyse binary data * **unzip** * extract compressed data ---- ### Tools used: * **base64** * base64 decode data * https://en.wikipedia.org/wiki/Base64 * **strings** * printable characters of file * **stegsolve** * hidden text in img * **gimp** * image manipulation --- ## Magic PNGs  ---- ### PNG Structure  source: http://www.libpng.org ---- ### PNG Chunks  source: http://www.libpng.org ---- ### PNG Signature  source: http://www.libpng.org ----  http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html ---- ### Used Tools * **google** * PNG structure * **xxd** * binary -> hex * **binwalk -W / colordiff** * compare files * **hexeditor** * make changes to file ---- ### PNG Tools * **pngcheck** * check validity of png * **pnginfo** * png information + errors * **pngchunks** * inspect single chunks ---- ### PNG Information * http://einstein.informatik.uni-oldenburg.de/rechnernetze/png.htm * https://www.w3.org/TR/PNG-Chunks.html * http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html * http://www.libpng.org/pub/png/book/chapter08.html --- <!-- .slide: data-background="https://media.giphy.com/media/hPrt0zRTMAVaugcgPf/giphy.gif" --> <div style="color: #fff; font-size: 100px;"> Now it's your turn :) </div> ---- Write-up link: https://its.fh-campuswien.ac.at/hackmd/s/HJP-O1jUE#