add overview section

5_theseus/2_overview.typ

@@ -0,0 +1,58 @@
+#import "../lib.typ": todo, APK, DEX, JAR, OAT, SDK, eg, ART, jm-note, jfl-note
+#import "@preview/diagraph:0.3.5": raw-render
+
+== Overview <sec:th-overview>
+
+Our objectif is to make available some dynamic information to any analysis tool able to analyse an Android #APK.
+To do so, we elected to follow the path of a few contributions we presented in @sec:bg such as DroidRA~@li_droidra_2016 and use instrumentation.
+Contrary to DroidRA, which use static analysis to compute the values of string and from that the methods used by reflection, we chose to dynamic analysis.
+This allows us to collect informations that are simply not available statically (#eg a string send from a remote command and control server).
+The tradeoff beeing the lack of exhaustiveness: dynamic analysis is known to have code coverage issues.
+
+#figure(
+  raw-render(
+    ```
+    digraph {
+      rankdir=LR
+
+      splines="ortho"
+
+
+      APK [shape=parallelogram]
+      "Automated Runner"
+      "Reverse Engineer"
+      "Dynamic Analysis" [shape=box]
+      "Runtime Information" [shape=parallelogram]
+      Transformation [shape=box]
+      "APK'" [shape=parallelogram]
+
+      APK:c -> "Dynamic Analysis"
+      "Automated Runner" -> "Dynamic Analysis" [style="dashed"]
+      "Reverse Engineer" -> "Dynamic Analysis" [style="dashed"]
+      "Dynamic Analysis" -> "Runtime Information"
+      APK -> Transformation
+      "Runtime Information" -> Transformation
+      Transformation -> "APK'"
+    }
+    ```,
+    width: 100%,
+    alt: (
+      "A diagram showing the process to transform an application.",
+      "Dotted arrows go from a \"Automated Runner\" and from \"Reverse Engineer\" to a box labeled \"Dynamic Analysis\", as well as plain arrow from \"APK\" to \"Dynamic Analysis\".",
+      "An arrow goes from \"Dynamic Analysis\" to \"Runtime Information\", then from \"Runtime Information\" to a box labeled \"Transformation\".",
+      "Another arrow goes from \"APK\" to \"Transformation\".",
+      "Finally, an arrow goes from \"Transformation\" to \"APK'\"."
+    ).join(),
+  ),
+  caption: [Process to add runtime information to an #APK],
+) <fig:th-process>
+
+@fig:th-process summarize our process.
+We first take an application that we analyse dynamically.
+To improve code coverage, either an reverse engineer or an automated runner will interact with the application.
+During this analysis, we use Frida to capture dynamic informations like the name of the methods called using reflection and bytecode loaded at runtime.
+This analysis described in @sec:th-dyn.
+
+The data collected by this analysis is then combined to application, transforming the application into another one that can then be analyzed further.
+We present the details of this transformation in @sec:th-trans.
+Since the transformation drives the data we need to collect, we have decided to place this section first in this chapter.