49 lines
3.3 KiB
Typst
49 lines
3.3 KiB
Typst
#import "../lib.typ": API, ie, todo
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== Introduction
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In order to understand the challenges of reverse engineering Android applications, we first need to understand some key concepts and specificities of Android.
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In particular, the format in wich application are distributed, as well as the runtime environment that runs those application, are very specific to Android.
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To handle those specificities, a reverse engineer must appropriate tools.
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Some of those tools are used recurrently, either by the reverse engineer themself, or as basis for other more complexe tools that implement more advance analysis techniques.
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Among those techniques, the ones that do not require to run the application are called static analysis.
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Over the time, many of those tools have been released.
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To compare those different tools, different benchmarks have been proposed, highlighting different strenght and weeknesses of each tools.
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Unfortunately static analysis has its limits.
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One such limit is that it cannot analysis what is not inside the application.
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Platform classes are classes that are present directly on the smartphone, and not in the application.
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Some of those classes are well known and taken into account by analysis tools, but the rest of those classes, often called _hidden #API;_, are not.
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In addition to platform classes, classes that are loaded dynamically (#ie at runtime) are also not always available to static analysis.
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This led static analysis tools to disregard the class loading process altogether, leaving the subject relativelly unexplored.
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When static analysis fails, for instance because of dynamic class loading, the reverse engineer will fallback dynamic analysis.
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Dynamic analysis is the counterpart of static analysis: the analysis is based on the analysis of the excecution of the application.
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Depending on the context, the reverse engineer will then alternate between different techniques, using previous results to improve the next iteration.
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Regrettably, analysis tools mostly return results in an ad hoc format, making it difficult to make other tools aware of the retrieved information.
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Some tools however encode their result in the form of a new augmented Android application.
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The idea beeing that any Android analysis tools must be able to handle an Android application in the first place, so it will have access to those new information.
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In this section, explore in more details those different aspects of Android reverse engineering.
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#todo[Plan d'annonce]
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#todo[Petit intro back platform classes, séparé de soa]
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#todo[Petit intro class loading séparé de soa]
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#todo[Bien séparer background et st-o-a]
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#todo[bien dédier des sections/sous section aux 3 problemes]
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#todo[synthese a la fin de chaque section soa des problemes]
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#todo[Problematique avant soa]
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#todo[
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plan:
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- 2.1 intro
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- 2.2 bases d'Android et RE (completer un peu pour souligner les besoins qui menes au pbs)
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- 2.3 Problématiques du RE (reprendre l'intro avec ce qui a été dit dans 2.2)
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apktool et androguard sont réutilisé, ca fait supposé qu'il y a peut être un peu de réutilisation
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on peut charger des classes, et dans le code d'android, on vois qu'en fait le classes loading est beaucoup plus important que ca
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c'est connus que cl + statique + ref = nono, tout les outils présentes leurs solutions d'une certaine facons
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- 2.4 State of the Art
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]
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