BBeOS/research/bootloader-analysis.md

BlackBerry Classic Q20 Bootloader Analysis

Boot Process Overview

Qualcomm MSM8960 Boot Sequence

1. PBL (Primary Boot Loader) - ROM-based, unchangeable
2. SBL (Secondary Boot Loader) - Loaded from eMMC, signed
3. ABOOT (Android Boot Loader) - LK-based bootloader
4. Kernel - Linux kernel with device tree
5. Init - System initialization

Bootloader Components

PBL (Primary Boot Loader)

• Location: ROM (read-only memory)
• Function: Initialize basic hardware, load SBL
• Security: Cannot be modified
• Features:
  • Basic hardware initialization
  • eMMC interface setup
  • SBL loading and verification

SBL (Secondary Boot Loader)

• Location: eMMC partition (usually 2MB)
• Function: Load and verify ABOOT
• Security: Signed with Qualcomm keys
• Features:
  • Hardware initialization
  • Security verification
  • ABOOT loading

ABOOT (Android Boot Loader)

• Location: eMMC boot partition
• Function: Load kernel and device tree
• Security: Can be locked/unlocked
• Features:
  • Fastboot protocol support
  • Recovery mode
  • Boot image verification

Boot Modes

Normal Boot

1. PBL → SBL → ABOOT → Kernel → Init
2. Standard boot sequence
3. Full security verification

Recovery Boot

1. PBL → SBL → Recovery Kernel
2. Minimal system for recovery
3. Limited security verification

Fastboot Mode

1. PBL → SBL → Fastboot
2. Development/debugging mode
3. Requires unlocked bootloader

EDL (Emergency Download Mode)

1. Hardware-based recovery
2. Bypasses normal boot sequence
3. Used for unbricking devices

Security Features

Secure Boot Chain

1. PBL verifies SBL signature
2. SBL verifies ABOOT signature
3. ABOOT verifies kernel signature
4. Kernel verifies initramfs signature

Signature Verification

• Algorithm: RSA-2048 or ECDSA
• Keys: Qualcomm and BlackBerry keys
• Verification: Hardware-based crypto engine

Bootloader Lock

• State: Usually locked by default
• Unlock: Requires developer mode
• Security: Prevents custom boot images

Debug Interfaces

Fastboot

• Protocol: USB-based
• Commands: flash, boot, reboot, etc.
• Access: Requires unlocked bootloader
• Security: Can be disabled

ADB (Android Debug Bridge)

• Protocol: USB-based
• Access: Requires developer mode
• Security: Can be disabled

Serial Console

• Interface: UART over USB
• Access: Hardware debug port
• Security: Usually disabled in production

JTAG

• Interface: 20-pin debug connector
• Access: Hardware debug port
• Security: Usually disabled in production

BlackBerry-Specific Modifications

BlackBerry 10 Bootloader

• Base: Modified LK (Little Kernel)
• Features: BlackBerry-specific security
• Modifications: Unknown (proprietary)

Security Enhancements

• BlackBerry Guardian: App verification
• BlackBerry Balance: Data separation
• BlackBerry Protect: Anti-malware

Unlock Possibilities

Developer Mode

• Method: Settings → Developer Options
• Requirements: Unknown
• Limitations: May not unlock bootloader

Bootloader Unlock

• Method: Fastboot oem unlock
• Requirements: Developer mode enabled
• Limitations: May void warranty

Hardware Unlock

• Method: JTAG/EDL
• Requirements: Hardware access
• Limitations: Requires specialized equipment

Research Status

Completed

• Basic boot sequence documented
• Security features identified
• Debug interfaces listed

In Progress

• Actual bootloader analysis
• Debug interface testing
• Unlock method verification

Needed

• Hardware access testing
• Bootloader reverse engineering
• Security bypass research

Tools and Methods

Software Tools

• Sachesi: BlackBerry firmware extractor
• BlackBerry Link: Official software
• Fastboot: Android bootloader tool
• ADB: Android debug bridge

Hardware Tools

• JTAG Debugger: Hardware debugging
• USB Analyzer: Protocol analysis
• Logic Analyzer: Signal analysis
• Oscilloscope: Timing analysis

Analysis Methods

• Firmware Extraction: Extract and analyze bootloader
• Reverse Engineering: Disassemble bootloader code
• Protocol Analysis: Analyze communication protocols
• Security Testing: Test security measures

Next Steps

Immediate

1. Obtain Device: Get physical access to Q20
2. Test Debug Interfaces: Try USB, serial, JTAG
3. Extract Firmware: Use Sachesi or similar tools
4. Analyze Bootloader: Reverse engineer bootloader

Short Term

1. Identify Unlock Methods: Find ways to unlock bootloader
2. Test Boot Modes: Verify different boot modes
3. Document Findings: Record all discoveries
4. Plan Development: Design custom bootloader

Long Term

1. Develop Custom Bootloader: Create replacement bootloader
2. Test Custom Kernel: Boot custom Linux kernel
3. Build Root Filesystem: Create minimal rootfs
4. Develop Drivers: Write hardware drivers

Challenges and Risks

Technical Challenges

• Proprietary Bootloader: BlackBerry-specific modifications
• Hardware Security: TrustZone and secure boot
• Limited Documentation: Scarce technical information
• Component Identification: Unknown exact hardware models

Legal and Ethical

• Warranty Void: Unlocking may void warranty
• Legal Issues: Potential legal restrictions
• Security Implications: May compromise device security
• Responsible Disclosure: Report security findings responsibly

Resource Requirements

• Hardware: Physical device and debug equipment
• Time: Significant time investment
• Expertise: Deep technical knowledge required
• Community: Limited community support