Introduction to Android Automotive OS Forensics

Android Automotive OS (AAOS) represents a significant shift in in-vehicle infotainment systems, providing a full Android stack directly integrated into the vehicle’s hardware. Unlike Android Auto, which is merely a projection of a smartphone interface, AAOS runs natively on the head unit, offering deeper integration with vehicle systems. This tight coupling makes AAOS a critical source of forensic data in investigations involving vehicle incidents, intellectual property theft, or privacy breaches. Traditional disk image forensics is often impractical or insufficient for AAOS, as many critical artifacts are volatile, residing only in active memory, process states, or live network connections. Live forensics, therefore, becomes paramount for capturing these ephemeral data points before they are lost.

The challenges of AAOS live forensics are multi-faceted. Devices are often embedded, requiring specialized access or a debug-enabled build. Security hardening, proprietary hardware, and varying OEM implementations can complicate data extraction. This article provides a comprehensive guide to capturing volatile data from a running AAOS system, focusing on practical techniques using standard Android debugging tools.

Understanding AAOS Architecture for Forensic Analysis

AAOS builds upon the standard Android Open Source Project (AOSP) but includes specific layers and services for vehicle integration, such as the Car Hardware Abstraction Layer (VHAL), Car Service, and various vehicle-specific apps. From a forensic perspective, this means data of interest might reside not only in typical Android locations (/data/data/<package>, databases, shared preferences) but also within vehicle-specific APIs, sensor data streams, and communication logs with ECUs. Volatile data can include:

• Active processes and open files
• Network connections and traffic
• System logs and kernel messages
• Memory contents of running applications and services
• Sensor readings (GPS, accelerometers, vehicle speed)
• User interface interactions and input events

Access typically relies on ADB (Android Debug Bridge), which can be enabled via developer options or dedicated diagnostic ports (e.g., USB-C debug ports, Ethernet adapters). Root access, while ideal, is often not available on production devices, necessitating techniques that work within the confines of non-rooted ADB shell access.

Prerequisites and Setup

Before beginning, ensure you have:

1. **Physical Access to the AAOS Device**: This is crucial for enabling developer options and connecting via USB or Ethernet.
2. **ADB Enabled**: Navigate to Developer Options (typically by tapping the ‘Build number’ multiple times in ‘About tablet/vehicle’). Enable ‘USB debugging’ and potentially ‘Wireless debugging’ if available and supported.
3. **ADB on Host Machine**: Ensure your forensic workstation has ADB tools installed and configured.
4. **Appropriate USB/Ethernet Adapters**: For connecting to the AAOS head unit.

# Verify ADB connection
adb devices

# Expected output:
# List of devices attached
# <device_serial_number>    device

Capturing Key Volatile Data Categories

1. Process Information and Open Files

Understanding what processes are running and what files they have open provides immediate insight into system activity. This includes user applications, system services, and vehicle-specific daemons.

Running Processes:

# List all running processes
adb shell ps -Ao PID,PPID,USER,CMD

# List top processes by CPU/Memory usage (similar to 'top' command)
adb shell top -b -n 1

Open Files and Network Connections (Requires lsof or similar, often not pre-installed):

If lsof is not available (which is common on stock Android systems), you can glean some information from /proc/<PID>/fd/ and /proc/net/. However, the comprehensive view that lsof provides is often superior. If root is available, lsof can be pushed to the device.

# List network connections (active sockets)
adb shell netstat -anp

# Examine open file descriptors for a specific process (e.g., PID 1234)
adb shell ls -l /proc/1234/fd/

# Get current working directory of a process
adb shell readlink /proc/1234/cwd

# Get command line arguments of a process
adb shell cat /proc/1234/cmdline

2. System Logs and Kernel Messages

Logs are a goldmine for understanding system events, errors, and application activity. AAOS generates various logs, including standard Android logs (logcat), kernel logs, and potentially vehicle-specific diagnostic logs.

Capturing Logcat Logs:

# Dump all existing logcat buffers (main, system, radio, events, crash)
adb shell logcat -b all -d > aaos_logcat_dump.txt

# Stream real-time logcat to a local file (Ctrl+C to stop)
adb logcat -b all > aaos_realtime_logcat.txt

# Filter logcat for specific tags (e.g., 'CarService')
adb logcat -s CarService:* > aaos_carservice_log.txt

Capturing Kernel Logs:

# Dump kernel ring buffer
adb shell dmesg > aaos_dmesg_output.txt

3. Memory Information and Partial Dumps

Full RAM acquisition on AAOS is often challenging without physical memory access tools or specialized debug kernels. However, valuable volatile memory information can still be extracted.

System Memory Information:

# Get overall system memory stats
adb shell cat /proc/meminfo > aaos_meminfo.txt

# List memory maps for a specific process (e.g., PID 1234)
adb shell cat /proc/1234/maps > aaos_pid1234_maps.txt

For more detailed memory analysis, if root access is available, tools like memdump or accessing /proc/<PID>/mem can allow for dumping specific memory regions. However, this is advanced and often requires careful handling due to permissions and potential system instability.

4. Network Activity and Configurations

Network forensics is critical for understanding communication patterns, connected services, and potential exfiltration attempts.

Network Interface Configuration:

# List all network interfaces and their configurations
adb shell ip a > aaos_ip_config.txt

# Show routing table
adb shell ip r > aaos_ip_route.txt

# Show ARP cache
adb shell ip n > aaos_arp_cache.txt

Active Network Connections:

# Display all active network connections
adb shell netstat -anp > aaos_netstat.txt

Capturing Network Traffic (if tcpdump is available or can be pushed):

If tcpdump (or a similar tool) is available on the AAOS device or can be pushed (requires root), you can capture live network traffic. Otherwise, this is very difficult from a remote shell.

# Example of capturing traffic on a specific interface (e.g., eth0)
# (Requires tcpdump binary on device and root)
# adb push <path_to_tcpdump_binary> /data/local/tmp/
# adb shell chmod 755 /data/local/tmp/tcpdump
# adb shell /data/local/tmp/tcpdump -i eth0 -s 0 -w /data/local/tmp/capture.pcap &
# ... perform actions ...
# adb shell killall tcpdump
# adb pull /data/local/tmp/capture.pcap .

5. Device State and Car Service Dumps

AAOS specific information can be highly valuable. The dumpsys command is a versatile tool for obtaining diagnostic output for various system services, including the Car Service.

# Dump all system services information
adb shell dumpsys > aaos_dumpsys_all.txt

# Dump information specifically for the Car Service
adb shell dumpsys activity service com.android.car > aaos_car_service_dump.txt

# Dump battery information (useful for power state analysis)
adb shell dumpsys battery > aaos_battery_dump.txt

# Dump WiFi information
adb shell dumpsys wifi > aaos_wifi_dump.txt

# Dump location service information
adb shell dumpsys location > aaos_location_dump.txt

6. File System State (Volatile Areas)

While a full file system image is not live forensics, checking volatile filesystem areas like /tmp or specific cache directories can yield valuable temporary files.

# List contents of /tmp
adb shell ls -laR /tmp > aaos_tmp_files.txt

# List contents of common cache directories (example)
adb shell ls -laR /data/system/cache > aaos_system_cache.txt

Data Exfiltration and Post-Acquisition

Once data is captured on the device, it needs to be securely pulled to the forensic workstation.

# Pull individual files or directories
adb pull /data/local/tmp/capture.pcap ./
adb pull /sdcard/some_app_log.txt ./

For larger datasets or when ADB pull is restricted for specific paths, consider archiving on the device and then pulling, or using network tools like Netcat if firewall rules allow.

# Example: Archiving logs and pulling (if busybox or similar is available)
# adb shell tar -czvf /data/local/tmp/volatile_data.tar.gz /tmp/*.txt /data/local/tmp/*.pcap
# adb pull /data/local/tmp/volatile_data.tar.gz ./

After acquisition, standard forensic analysis tools (e.g., Volatility Framework for memory dumps if a full dump was possible, Wireshark for PCAPs, log analyzers) can be used to interpret the collected volatile data.

Challenges and Limitations

• **Root Access**: Many advanced techniques (e.g., full RAM dumps, installing custom tools like tcpdump or lsof) require root, which is typically unavailable on production AAOS units.
• **OEM Variations**: Implementations vary significantly between vehicle manufacturers, affecting debug port availability, ADB permissions, and accessible system services.
• **Time Sensitivity**: Volatile data changes rapidly. The faster the acquisition, the more accurate the forensic snapshot.
• **System Stability**: Aggressive live acquisition can impact system performance or even cause crashes, especially on resource-constrained embedded systems.
• **Security Enhancements**: Modern AAOS versions integrate robust security features that actively resist unauthorized data extraction, making forensic efforts more challenging.

Conclusion

Live forensics on Android Automotive OS is a complex yet indispensable process for incident response and digital investigations involving modern vehicles. By understanding the unique architecture of AAOS and leveraging standard Android debugging tools, investigators can effectively capture critical volatile data that might otherwise be lost. While challenges like root access and OEM variations persist, the techniques outlined here provide a robust foundation for acquiring ephemeral evidence from running vehicle systems, bridging a significant gap in traditional automotive forensics.