/Recent content in Home on phakeobjHugoen-usTue, 20 Jul 2021 15:11:14 +0000/posts/googlectf-2021-compress/Tue, 20 Jul 2021 15:11:14 +0000/posts/googlectf-2021-compress/<blockquote> <p>My friend developed a custom compression algorithm, but doesn&rsquo;t want to share the format documentation. He keeps it on his demo server - why don&rsquo;t you try to steal it?</p></blockquote> <h2 id="reconnaissance">Reconnaissance</h2> <p>The challenge zip file consisted a single binary executable file called <code>compress</code>. we started off conservatively, by running <code>checksec</code> to understand what are we dealing with here.</p> <pre tabindex="0"><code>phakeobj@localbox:~/ctf/google-2021/compress$checksec compress [*] &#39;/home/phakeobj/ctf/google-2021/compress/compress&#39; Arch: amd64-64-little RELRO: Full RELRO Stack: Canary found NX: NX enabled PIE: PIE enabled FORTIFY: Enabled </code></pre><p>After getting to know the security properties of the executable, we played around with it, in hope to get some understanding of the functionality and where would it make sense to find a bug. We started off by trying out the 3 available options in the menu.</p>/posts/gigacage/Sun, 25 Aug 2019 16:13:30 +0300/posts/gigacage/A WebKit Exploit Mitigation Technique