BlackHat Android Hacking

This module is where theory turns into a tangible threat. We dive deep into the practical process of creating a malicious Android Application Package (APK) that can provide you with remote access to a victim’s device. You will learn to weaponize a common app by embedding a stealthy backdoor, obfuscating the code to evade detection, and preparing it for deployment. This hands-on module covers the essential lifecycle of an Android malware attack, from initial infection vector to establishing a persistent remote shell.

What You Will Learn

Part 1: Deconstructing the Standard Payload

• Limitations of msfvenom: Analysis of how EDR/AV solutions fingerprint Metasploit payloads (artifacts, code patterns, network signatures).

• The Anatomy of a Shellcode Stager: Understanding the role of the stager and the final payload in memory.

• Introduction to Custom C2 Protocols: Moving away from Meterpreter’s default communication to bespoke, encrypted protocols (e.g., using WebSockets over TLS, or blending traffic with legitimate apps like Discord or Telegram Bots).

Part 2: Building a Custom Payload from Scratch

• Native Code Payloads (JNI/NDK):

  • Writing payload logic in C/C++ for execution speed and deeper system integration.

  • Leveraging the Android NDK to create native libraries (.so files) loaded by a minimal Java wrapper.

  • Benefits for anti-analysis and bypassing runtime sandboxes.

• Reflective Loading & In-Memory Execution:

  • Techniques to load a DEX file or native library directly from memory, avoiding the classes.dex on disk.

  • Implementing “fileless” execution techniques to leave minimal forensic traces.

• Custom Command and Control (C2):

  • Designing a secure, asynchronous communication channel.

  • Implementing key features: beaconing, job retrieval, and result exfiltration.

  • Using covert channels (e.g., ICMP, DNS tunneling) for network egress in restricted environments.

Part 3: Advanced Evasion & Anti-Analysis

• Runtime Environment Detection:

  • Detecting and bypassing emulators, debuggers, and popular analysis frameworks (e.g., Xposed, Frida).

  • Checking for root, USB debugging status, and uncommon system properties.

• Advanced Obfuscation:

  • Control-flow flattening and string encryption for native code.

  • Using tools like OLLVM or Tigress for compiler-level obfuscation.

  • Dynamic code loading (DexClassLoader) to hide core functionality.

• Signature Evasion: Modifying payload hashes and structural characteristics on-the-fly per installation.

Part 4: Deep Persistence Mechanisms

• Moving Beyond android.permission.BIND_DEVICE_ADMIN:

  • Abusing accessibility services for unremovable persistence.

  • Achieving persistence through vendor-specific APIs or pre-installed app vulnerabilities.

• Forensic-Aware Persistence:

  • Hiding application icons and removing the app from the launcher and settings menu.

  • Masquerading as a core system process (com.android.systemui).

  • Leveraging JobScheduler and WorkManager for time-based or event-based beaconing that conserves battery and avoids suspicion.

Part 5: Post-Exploitation at the System Level

• Silent Data Exfiltration: Programmatically accessing and uploading data from sources like Secure Folder, WhatsApp media, and 2FA app backups without user interaction.

• Advanced Reconnaissance:

  • Harvesting credentials from installed browsers and password managers.

  • Tracking user location and behavior through system logs and sensor data.

• Living Off the Land (LOTL): Using legitimate, pre-installed system tools and apps (am, pm, content) to perform actions and avoid bringing in custom binaries.

Hands-On Lab: The Phantom Implant
You will build a sophisticated implant in a controlled lab environment:

1. Develop a Native Payload: Write a core beaconing function in C, compile it with the NDK, and obfuscate the binary.

2. Create a Minimalist Loader: Build a thin Android app that uses Reflective DLL Loading techniques to execute the native payload from an encrypted asset, avoiding disk writes.

3. Implement a Stealth C2: Set up a Python-based C2 server using WebSockets over TLS (WSS). The payload will beacon at random intervals, mimicking legitimate app traffic.

4. Achieve Deep Persistence: Configure the implant to restart itself using an AlarmManager and BroadcastReceiver upon a “BOOT_COMPLETED” event, while hiding its icon.

5. Test Evasion: Run the final payload against standard AV and advanced mobile security solutions to verify its stealth.