https://b17fr13nds.github.io/tags/parser/Recent content in Parser on bitfriends' blogHugoenMon, 02 Sep 2024 20:24:09 +0200https://b17fr13nds.github.io/posts/the_ring_bhmea/Mon, 02 Sep 2024 20:24:09 +0200https://b17fr13nds.github.io/posts/the_ring_bhmea/<p>I had a fun time playing BlackHat MEA CTF. This pwn challenge was particulary nice.</p> <p>In &ldquo;the ring&rdquo; you were given a <code>FLAC</code> audio file parser, written in C++. You can provide such a custom audio file and get presented the output of the program. Notice that there is a Python wrapper handling the file and outputs readable text only.</p> <p>Now the general functionality of the program: The program checks the magic bytes first (<code>#define FLAC_MAGIC 0x664c6143U</code>) and then immedeately starts looking for the initial <code>TYPE_STREAMINFO</code> block, which may be followed by more blocks.</p>