525 lines
20 KiB
HTML
525 lines
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HTML
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<head>
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<meta name="generator" content="pandoc">
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<meta name="author" content="Stefan Friese">
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<title>Introduction to Reverse Engineering</title>
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<link rel="stylesheet" href="https://unpkg.com/reveal.js@^4//dist/theme/dracula.css" id="theme">
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</head>
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<body>
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<div class="reveal">
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<div class="slides">
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<section id="title-slide">
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<h1 class="title">Introduction to Reverse Engineering</h1>
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<p class="author">Stefan Friese</p>
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<p class="date">02 November, 2023</p>
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</section>
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<section id="topics" class="slide level1">
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<h1>Topics</h1>
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<ul>
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<li class="fragment">Effective Reverse Engineering</li>
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<li class="fragment">Reversing with Ghidra</li>
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</ul>
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</section>
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<section class="slide level1">
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<h2 id="how-do-you-reverse">How Do You Reverse</h2>
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<p>Reverse Engineering demands a lot of knowledge in multiple
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fields.</p>
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<p><strong>Some topics are</strong></p>
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<ul>
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<li class="fragment">Assembly Language</li>
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<li class="fragment">ANSI C</li>
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<li class="fragment">Other Languages</li>
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<li class="fragment">Syscalls</li>
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<li class="fragment">Cryptography</li>
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</ul>
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</section>
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<section class="slide level1">
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<p>How do you reverse engineer without knowing little about these
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topics?</p>
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</section>
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<section class="slide level1">
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<h2 id="reversing-is-work">Reversing is Work</h2>
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<p>Work is a product of power by time.<br />
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<code>P</code> is your power to solve an issue.</p>
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<p><code>W = P x t</code></p>
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<p>The smarter you tackle work, the less time you need to solve an
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issue.</p>
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</section>
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<section class="slide level1">
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<h2 id="knowledge-is-a-map">Knowledge is a Map</h2>
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<p>You conventiently drive around the city using the underground. That’s
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how you get to know the main spots of the city.</p>
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<p><img src="./images/london_underground.jpg" alt="London Underground" width="50%" height="auto"></p>
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</section>
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<section class="slide level1">
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<h2 id="knowledge-is-a-map-1">Knowledge is a Map</h2>
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<p>Invest some time and explore deeper on foot. That’s how you get to
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know the back alleys.</p>
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<p><img src="./images/london_by_foot.jpg" alt="London by Foot" width="50%" height="auto"></p>
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</section>
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<section id="ghidra-an-overview" class="slide level1">
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<h1>Ghidra – an Overview</h1>
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</section>
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<section class="slide level1">
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<figure>
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<img data-src="./images/Ghidra-Overview.png"
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alt="Main View of Ghidra" />
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<figcaption aria-hidden="true">Main View of Ghidra</figcaption>
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</figure>
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</section>
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<section class="slide level1">
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<h2 id="watch-out-for-low-hanging-fruits">Watch Out for Low Hanging
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Fruits</h2>
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</section>
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<section class="slide level1">
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<ul>
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<li class="fragment">Data Segment</li>
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<li class="fragment">Names of Functions</li>
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<li class="fragment">Conditions & Comparisons</li>
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<li class="fragment">Strings: Usernames, Passwords</li>
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<li class="fragment">URLs, IP & Port Numbers</li>
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</ul>
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<p><strong>Do not try to understand the whole code at once, it will only
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drive you mad.</strong></p>
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</section>
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<section class="slide level1">
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<h3 id="data-segments">Data Segments</h3>
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<figure>
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<img data-src="./images/data-segments.png"
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alt="A look into the read only data segment" />
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<figcaption aria-hidden="true">A look into the read only data
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segment</figcaption>
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</figure>
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</section>
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<section class="slide level1">
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<h3 id="name-of-functions">Name of Functions</h3>
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<figure>
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<img data-src="./images/symbol-tree.png"
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alt="Functions contained in the binary a.k.a. Symbol Tree" />
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<figcaption aria-hidden="true">Functions contained in the binary a.k.a.
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Symbol Tree</figcaption>
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</figure>
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</section>
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<section class="slide level1">
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<h3 id="conditions-comparisions">Conditions & Comparisions</h3>
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<p><img src="./images/decompiled-code.png" alt="Input is Compared to a Hard Coded String" width="50%" height="auto"></p>
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<p>Input is compared to a hard coded string</p>
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</section>
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<section class="slide level1">
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<h3 id="function-graph">Function Graph</h3>
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<p><img src="./images/function-graph.png" alt="Take a Look at the Flow Graph of Functions" width="50%" height="auto"></p>
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<p>Take a look at the flow graph of functions</p>
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</section>
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<section class="slide level1">
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<h3 id="strings">Strings</h3>
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<p><img src="./images/defined-strings-menu.png" alt="Open the Defined Strings Menu" width="50%" height="auto"></p>
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<p>Strings can not only be located in data but also in other code
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segments, sometimes obfuscated</p>
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</section>
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<section class="slide level1">
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<h3 id="strings-1">Strings</h3>
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<figure>
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<img data-src="./images/defined-strings.png" alt="An old friend" />
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<figcaption aria-hidden="true">An old friend</figcaption>
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</figure>
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</section>
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<section class="slide level1">
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<h3 id="do-it-yourselves">Do It Yourselves!</h3>
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<ul>
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<li class="fragment"><a href="https://ghidra-sre.org/">Download
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Ghidra</a></li>
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<li class="fragment"><a href="https://crackmes.one">Download binaries at
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crackmes.one</a></li>
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<li class="fragment"><a href="https://hackthebox.eu">Find more binaries
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on hackthebox</a></li>
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<li class="fragment"><a href="https://tryhackme.com">Or Find even more
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on tryhackme</a></li>
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<li class="fragment">Download firmware of your favorite IoT
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appliances</li>
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</ul>
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</section>
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<section class="slide level1">
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<h2 id="a-word-on-binary-obfuscation">A Word On Binary Obfuscation</h2>
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<p>Software Obfuscation was born in 1984 at the <a
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href="https://ioccc.org/">International Obfuscated C Code
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Contest</a></p>
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<p><img src="./images/donut.gif" alt="A donut as code compiles to a spinning donut by Jim Hague" width="50%" height="auto"></p>
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</section>
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<section class="slide level1">
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<h3 id="what-exactly-might-be-obfuscated-in-your-code">What Exactly
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might be Obfuscated in Your Code?</h3>
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<section>
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<a
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href="https://cybersecurity.springeropen.com/track/pdf/10.1186/s42400-020-00049-3.pdf">Layered
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obfuscation: a taxonomy of software obfuscation techniques for layered
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security by Hui Xu et. al</a>
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</section>
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<section>
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<ul>
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<li class="fragment">Code Element Layers
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<ul>
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<li class="fragment">Layout</li>
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<li class="fragment">Controls</li>
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<li class="fragment">Data</li>
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<li class="fragment">Methods</li>
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<li class="fragment">Classes</li>
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</ul></li>
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</ul>
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</section>
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<section>
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<ul>
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<li class="fragment">Component
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<ul>
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<li class="fragment">Library Calls</li>
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<li class="fragment">Used Resources</li>
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</ul></li>
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<li class="fragment">Application Layer
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<ul>
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<li class="fragment">DRM System</li>
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<li class="fragment">Neural Networks</li>
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</ul></li>
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</ul>
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</section>
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</section>
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<section class="slide level1">
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<h2 id="techniques-of-obfuscation">Techniques of Obfuscation</h2>
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</section>
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<section class="slide level1">
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<h3 id="splitting-merging-of-strings">Splitting & Merging of
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Strings</h3>
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<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">a</span> = <span class="st">"BABE"</span></span>
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<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="ex">b</span> = <span class="st">"CAFFEE"</span></span>
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<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="ex">f</span><span class="st">"{b}{a}"</span></span></code></pre></div>
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<p><a href="https://github.com/mandiant/flare-floss/">String
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Deobfuscation with FLOSS</a></p>
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</section>
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<section class="slide level1">
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<h2 id="packing">Packing</h2>
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<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a> <span class="ex">ooooo</span> ooo ooooooooo. ooooooo ooooo</span>
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<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">`</span><span class="ex">888</span><span class="st">' `8'</span> <span class="kw">`</span>888 <span class="kw">`</span><span class="ex">Y88.</span> <span class="kw">`</span>8888 d8<span class="st">'</span></span>
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<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="st"> 888 8 888 .d88'</span> Y888..8P</span>
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<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a> <span class="ex">888</span> 8 888ooo88P<span class="st">' `8888'</span></span>
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<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a> <span class="ex">888</span> 8 888 .8PY888.</span>
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<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a> <span class="kw">`</span><span class="ex">88.</span> .8<span class="st">' 888 d8'</span> <span class="kw">`</span>888b</span>
|
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<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">`</span><span class="ex">YbodP</span><span class="st">' o888o o888o o88888o</span></span></code></pre></div>
|
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<p><a href="https://upx.github.io/">UPX Packer/Unpacker</a></p>
|
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</section>
|
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<section class="slide level1">
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<h3 id="mangling">Mangling</h3>
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<section>
|
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<pre><code data-trim data-noescape>
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c++filt
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_ZNSt7__cxx1114collate_bynameIcEC2ERKNS_12basic_stringIcSt11char_traitsIcESaIcEEEm
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std::__cxx11::collate_byname<char>::collate_byname(std::__cxx11::basic_string<char,
|
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std::char_traits<char>, std::allocator<char> > const&, unsigned long)
|
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</code></pre>
|
||
</section>
|
||
<section>
|
||
<a href="https://demangler.io/" alt="demangler">Online Demangler</a>
|
||
</section>
|
||
</section>
|
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<section class="slide level1">
|
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<h3 id="code-elements">Code Elements</h3>
|
||
<ul>
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<li class="fragment">Adding Unnecessary Instructions</li>
|
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<li class="fragment">Changing Control Flows</li>
|
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<li class="fragment">Protecting Data</li>
|
||
</ul>
|
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<p><img src="./images/spaghetti.jpg" alt="Convoluted Code" width="30%" height="30%"></p>
|
||
</section>
|
||
<section class="slide level1">
|
||
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<h3 id="deobfuscation-tools">Deobfuscation Tools</h3>
|
||
<ul>
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<li class="fragment">DotNet
|
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<ul>
|
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<li class="fragment"><a href="https://github.com/de4dot/de4dot">de4dot
|
||
Deobfuscator and Unpacker</a></li>
|
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<li class="fragment"><a href="https://github.com/dnSpy/dnSpy">dnSpy
|
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Debugger and Assembly Editor</a></li>
|
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<li class="fragment"><a
|
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href="https://github.com/icsharpcode/ILSpy">ILSpy Decompiler instead of
|
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Ghidra</a></li>
|
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</ul></li>
|
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</ul>
|
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</section>
|
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</div>
|
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</div>
|
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|
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<script src="https://unpkg.com/reveal.js@^4//dist/reveal.js"></script>
|
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|
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<script src="https://unpkg.com/reveal.js@^4//plugin/notes/notes.js"></script>
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<script src="https://unpkg.com/reveal.js@^4//plugin/zoom/zoom.js"></script>
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<script>
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// Full list of configuration options available at:
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// https://revealjs.com/config/
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|
||
hashOneBasedIndex: false,
|
||
|
||
// Flags if we should monitor the hash and change slides accordingly
|
||
respondToHashChanges: true,
|
||
|
||
// Push each slide change to the browser history
|
||
history: false,
|
||
|
||
// Enable keyboard shortcuts for navigation
|
||
keyboard: true,
|
||
|
||
// Enable the slide overview mode
|
||
overview: true,
|
||
|
||
// Disables the default reveal.js slide layout (scaling and centering)
|
||
// so that you can use custom CSS layout
|
||
disableLayout: false,
|
||
|
||
// Vertical centering of slides
|
||
center: true,
|
||
|
||
// Enables touch navigation on devices with touch input
|
||
touch: true,
|
||
|
||
// Loop the presentation
|
||
loop: false,
|
||
|
||
// Change the presentation direction to be RTL
|
||
rtl: false,
|
||
|
||
// see https://revealjs.com/vertical-slides/#navigation-mode
|
||
navigationMode: 'default',
|
||
|
||
// Randomizes the order of slides each time the presentation loads
|
||
shuffle: false,
|
||
|
||
// Turns fragments on and off globally
|
||
fragments: true,
|
||
|
||
// Flags whether to include the current fragment in the URL,
|
||
// so that reloading brings you to the same fragment position
|
||
fragmentInURL: true,
|
||
|
||
// Flags if the presentation is running in an embedded mode,
|
||
// i.e. contained within a limited portion of the screen
|
||
embedded: false,
|
||
|
||
// Flags if we should show a help overlay when the questionmark
|
||
// key is pressed
|
||
help: true,
|
||
|
||
// Flags if it should be possible to pause the presentation (blackout)
|
||
pause: true,
|
||
|
||
// Flags if speaker notes should be visible to all viewers
|
||
showNotes: false,
|
||
|
||
// Global override for autoplaying embedded media (null/true/false)
|
||
autoPlayMedia: null,
|
||
|
||
// Global override for preloading lazy-loaded iframes (null/true/false)
|
||
preloadIframes: null,
|
||
|
||
// Number of milliseconds between automatically proceeding to the
|
||
// next slide, disabled when set to 0, this value can be overwritten
|
||
// by using a data-autoslide attribute on your slides
|
||
autoSlide: 0,
|
||
|
||
// Stop auto-sliding after user input
|
||
autoSlideStoppable: true,
|
||
|
||
// Use this method for navigation when auto-sliding
|
||
autoSlideMethod: null,
|
||
|
||
// Specify the average time in seconds that you think you will spend
|
||
// presenting each slide. This is used to show a pacing timer in the
|
||
// speaker view
|
||
defaultTiming: null,
|
||
|
||
// Enable slide navigation via mouse wheel
|
||
mouseWheel: false,
|
||
|
||
// The display mode that will be used to show slides
|
||
display: 'block',
|
||
|
||
// Hide cursor if inactive
|
||
hideInactiveCursor: true,
|
||
|
||
// Time before the cursor is hidden (in ms)
|
||
hideCursorTime: 5000,
|
||
|
||
// Opens links in an iframe preview overlay
|
||
previewLinks: false,
|
||
|
||
// Transition style (none/fade/slide/convex/concave/zoom)
|
||
transition: 'slide',
|
||
|
||
// Transition speed (default/fast/slow)
|
||
transitionSpeed: 'default',
|
||
|
||
// Transition style for full page slide backgrounds
|
||
// (none/fade/slide/convex/concave/zoom)
|
||
backgroundTransition: 'fade',
|
||
|
||
// Number of slides away from the current that are visible
|
||
viewDistance: 3,
|
||
|
||
// Number of slides away from the current that are visible on mobile
|
||
// devices. It is advisable to set this to a lower number than
|
||
// viewDistance in order to save resources.
|
||
mobileViewDistance: 2,
|
||
|
||
// reveal.js plugins
|
||
plugins: [
|
||
RevealNotes,
|
||
RevealSearch,
|
||
RevealZoom
|
||
]
|
||
});
|
||
</script>
|
||
</body>
|
||
</html>
|