APK-Simplifier

Android packages (.apk files) nowadays contain a large amount of (third-party) libraries. APK-Simplifier allows to detect library classes that have not been tampered with. To do so JPlag, a plagiarism checker (or clone detector), is used. APK-Simplifier supports two phases:

1. Parsing Phase:
   • The input app is scanned for libraries.
   • Each library found is downloaded from a Google repository (e.g. https://dl.google.com/android/maven2/androidx/activity/activity/1.0.0/activity-1.0.0.aar).
   • The individual classes are extracted (and decompiled) from the library and from the app.
   • Both version of each seemingly same class are forwarded to JPlag to check if they are equal (or similar) up to a certain configurable threshold.
   • A list of equal and thereby trusted classes is output at the end of the first phase.

1. Simplification Phase:
   • The trusted library classes are removed from the app by employing Soot.
   • This step is performed via the SIMPLIFY operator of the AQL-System.

!!! Please note, the SIMPLIFY operator is not yet included in the AQL-System, however, it will be included with its next release. Same holds for the AQL-System dependency that denoted in this projects pom.xml !!!

Building

Simply run Maven (mvn) inside the projects directory.
Dependency AQL-System 2.0.1 no available, yet. Thus, please use the pre-compiled version (see Releases).

Usage

!!! Dex2Jar must be installed and accessible. !!!

Before you are ready to simplify an app, please create or adapt the tool’s configuration file (simplifyParser.properties). Here is an example of its content:

dex2jarPath=/path/to/dex2jar/d2j-dex2jar
threshold=70.0

dex2jarPath must refer to the d2j-dex2jar executable of Dex2Jar. The value given as threshold is used as similarity score minimum - with respect to the given example, only library classes that are 70% or more equal are removed.

To finally execute the tool run:

java -jar SimplifyParser.jar app.apk [output.txt]

app.apk is a placeholder of the app you want to simplify. The second parameter specifies the output file. This parameter is optional - by default the file output.txt is created.

Publications

• Scaling Arbitrary Android App Analyses (Felix Pauck)
  A-Mobileq@ASE 2022 (to appear)

License

APK-Simplifier is licensed under the GNU General Public License v3 (see LICENSE).

Contact

Felix Pauck (FoelliX)
Paderborn University
fpauck@mail.uni-paderborn.de
http://www.FelixPauck.de