Android Reverse Engineering: Process, Tools, and Code Examples

Android reverse engineering is the process of dissecting an APK to understand its inner workings, modify behavior, and analyze security vulnerabilities.

The typical workflow includes:

Obtain the target APK file.

Decompile the APK using tools such as apktool, dex2jar, or JADX.

Analyze the source code (Smali, Java) and resources.

Modify the code or resources as needed.

Recompile the APK with apktool and sign it using jarsigner.

Test the modified APK on a device.

Key tools mentioned are adb for extracting APKs, JADX, JD‑GUI for viewing Java code, and Apktool for de/compiling and handling Smali files. Example adb commands are shown to list devices, retrieve package name, locate the APK path, and pull the file.

Smali syntax is explained with examples of class declarations, fields, and methods. Code snippets demonstrate how to insert logging calls via a custom LogUtils class.

# 显示已连接adb的设备列表
$ adb devices
>>输出:
List of devices attached
MDX5T20911002698 device
# 1. 打开目标应用，获取当前应用的相关包名
adb shell dumpsys window | grep mCurrentFocus
>>输出:
 mCurrentFocus=Window{4c1c551 u128 com.tencent.mm/com.tencent.mm.ui.LauncherUI}
# 2. 获取对应包名在设备中的apk包路径
adb shell pm path com.tencent.mm
>>输出：
package:/data/app/~~.../base.apk
# 3. 将相关apk包，下载到本地设备
adb pull /data/app/~~.../base.apk ./
>>输出：
1 file pulled. 35.4 MB/s (249620210 bytes in 6.731s)

Rebuilding the APK is done with apktool b <directory> , producing an unsigned package that must be signed with jarsigner before installation.

The article emphasizes that while this guide provides a basic introduction, real‑world security defense requires deeper analysis and continuous updates.