Info Obfuscated methods

Description

Obfuscation refers to methods to obscure code and make it hard to understand. Compiled Java classes can be decompiled if there is no obfuscation during compilation step.

Adversaries can steal code and repurpose it and sell it in a new application or create a malicious fake application based on the initial one.

Code obfuscation only slows the attacker from reverse engineering but does not make it impossible.

Recommendation

Design the application to add the following protections and slow reverse engineering of the application:

  • Obfuscate Java source code with tools like Proguard or Dexguard
  • buildTypes {
            release {
                minifyEnabled true
                proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
            }
        }
  • Verification application signing certificate during runtime by checking context.getPackageManager().signature
  • Check application installer to ensure it matches the Android Market by calling context.getPackageManager().getInstallerPackageName
  • Check running environment at runtime
  • private static String getSystemProperty(String name) throws Exception {
        Class systemPropertyClazz = Class.forName("android.os.SystemProperties");
        return (String) systemPropertyClazz.getMethod("get", new Class[] { String.class }).invoke(systemPropertyClazz, new Object[] { name });
    }
    
    public static boolean checkEmulator() {
    
        try {
            boolean goldfish = getSystemProperty("ro.hardware").contains("goldfish");
            boolean qemu = getSystemProperty("ro.kernel.qemu").length() > 0;
            boolean sdk = getSystemProperty("ro.product.model").equals("sdk");
    
            if (qemu || goldfish || sdk) {
                return true;
            }
    
        } catch (Exception e) {
        }
    
        return false;
      }
  • Check debug flag at runtime
  • context.getApplicationInfo().applicationInfo.flags & ApplicationInfo.FLAG_DEBUGGABLE;

Technical details
PackageObfuscated
android.support.print False
retrofit False
a.a.a True
android.support.coreui False
android.support.mediacompat False
android.support.slidingpanelayout False
android.support.v4 False
android.support.fragment False
b True
android.support.loader False
android.support.coreutils False
android.support.interpolator False
android.support.cursoradapter False
android.support.documentfile False
android.support.constraint False
android.support.multidex False
android.support.design False
android.support.drawerlayout False
io.card.payment True
androidx.versionedparcelable True
android.support.compat False
c True
org.apache.http False
android.support.customview False
android.support.transition False
org.spongycastle.jcajce True
android.support.annotation False
org.spongycastle.b True
org.spongycastle.a True
android.support.coordinatorlayout False
android.support.localbroadcastmanager False
android.support.swiperefreshlayout False
org.spongycastle.c True
org.spongycastle.d True
org.bouncycastle False
android.support.asynclayoutinflater False
okhttp3 False
org.spongycastle.jce False
android.arch.lifecycle True