Detailed Build Instructions for Cuckoo Loader

This guide provides comprehensive instructions for building the Nest Thermostat DFU exploit, covering critical details missing from the README.

System Requirements

Linux Distribution: Ubuntu/Debian-based (tested on Ubuntu 25.10)
Architecture: x86_64 (64-bit) - special steps required for 32-bit toolchain compatibility
RAM: At least 4GB recommended (kernel compilation is memory-intensive)
Disk Space: ~500MB for sources + toolchains + builds
USB Access: Root/sudo access for USB device passthrough (if using VM)

Prerequisites and Dependencies

1. Install Required System Packages

Before building, install these essential packages:

sudo apt-get update
sudo apt-get install -y \
    build-essential \
    git \
    wget \
    tar \
    bzip2 \
    pkg-config \
    u-boot-tools \
    libusb-1.0-0-dev \
    libc6-i386 \
    lib32stdc++6 \
    lib32z1

Package Explanations:

build-essential: GCC, make, and basic build tools
pkg-config: Required for libusb detection during omap_loader build
u-boot-tools: Provides mkimage command for creating uImage kernel images
libusb-1.0-0-dev: USB library development headers (version 1.0, not 0.1)
libc6-i386 lib32stdc++6 lib32z1: 32-bit compatibility libraries for the ARM toolchain

2. 64-bit System Compatibility

The ARM toolchain (arm-2008q3) was compiled for 32-bit systems. On 64-bit systems, you'll encounter "cannot execute: required file not found" errors.

Solution: Install 32-bit compatibility libraries (included in the apt command above).

Verification: Test the toolchain after installation:

# After running build.sh once (which downloads the toolchain)
~/cuckoo_loader/build/toolchain/arm-2008q3/bin/arm-none-linux-gnueabi-gcc --version

If you still get "cannot execute" errors, ensure all 32-bit libs are installed.

Build Process

Step 1: Clone the Repository

git clone https://github.com/ajb142/cuckoo_loader.git
cd cuckoo_loader

Step 2: Run the Build Script

./build.sh

What the build script does:

Creates build/ directory
Downloads CodeSourcery ARM toolchain (arm-2008q3)
Extracts and sets up toolchain in build/toolchain/
Downloads original NestDFUAttack repository
Downloads x-loader source from Google
Downloads modified omap_loader from GitHub
Cross-compiles x-loader for ARM
Cross-compiles u-boot with Nest patches
Cross-compiles Linux kernel with exploit modifications
Compiles host omap_loader tool
Copies all binaries to build/bin/

Expected build time: 15-30 minutes depending on system performance.

Step 3: Verify Build Success

Check that these files were created:

ls -lh build/bin/nest/
# Should show: x-load.bin, u-boot.bin, uImage

ls -lh build/bin/host/
# Should show: omap_loader

Troubleshooting Common Issues

Issue: "arm-none-linux-gnueabi-gcc: cannot execute: required file not found"

Cause: Missing 32-bit compatibility libraries on 64-bit system.

Solution: Install the 32-bit libs:

sudo apt-get install libc6-i386 lib32stdc++6 lib32z1

Issue: "mkimage" command not found

Cause: Missing u-boot-tools package.

Solution:

sudo apt-get install u-boot-tools

Then rebuild the Linux kernel:

cd build/NestDFUAttack-master/Dev/linux
make uImage

Issue: libusb.h not found or compilation errors in omap_loader

Cause: Wrong libusb version or missing pkg-config.

Solutions:

Ensure libusb-1.0-0-dev is installed (not libusb-dev)
Ensure pkg-config is installed
If build fails, manually compile omap_loader:

cd build/omap_loader
git checkout send_correct_jump_for_nest
make clean
make

Issue: "dirname: missing operand" errors

Cause: PATH not set correctly for toolchain.

Workaround: The build script should handle this, but if issues persist, manually set PATH:

export PATH="$PATH:$(pwd)/build/toolchain/arm-2008q3/bin"

Issue: Build hangs or runs out of memory

Cause: Insufficient RAM for parallel compilation.

Solution: Limit parallel jobs:

# Instead of ./build.sh, use:
make -C build/NestDFUAttack-master/Dev/linux -j1 uImage

USB Device Setup (for VM users)

If running in a VM (like QEMU/KVM), you need to passthrough the Nest device:

1. Identify the USB Device

When Nest is in DFU mode (hold screen for 10+ seconds), it appears as:

Vendor ID: 0451
Product ID: d00e
Description: "Texas Instruments OMAP3630"

2. Create USB Device XML

cat > /tmp/usb-device.xml << 'EOF'
<hostdev mode='subsystem' type='usb' managed='yes'>
  <source>
    <vendor id='0x0451'/>
    <product id='0xd00e'/>
  </source>
</hostdev>
EOF

3. Attach to VM

sudo virsh attach-device your-vm-name /tmp/usb-device.xml

Note: You may need to detach/re-attach as the device ID changes each DFU attempt.

Running the Exploit

1. Prepare the Nest Device

Power on the Nest thermostat
Press and hold the screen for approximately 10 seconds
The screen should go blank and the device enters DFU mode

2. Run the Exploit

./load_firmware.sh

Expected output (similar to):

[+] jump command: 0x6a425355
[+] jump command le: 0x6a425355
OMAP Loader 1.0.0
File 'x-load.bin' at 0x40200000, size 27876
File 'u-boot.bin' at 0x80100000, size 246572
File 'uImage' at 0x80a00000, size 6974112
[+] scanning for USB device matching 0451:d00e...
[+] successfully opened 0451:d00e (Texas Instruments OMAP3630)
[+] got ASIC ID - Num Subblocks [05], Device ID Info [01050136300707], Reserved [13020100], Ident Data [1215010000000000000000000000000000000000000000], Reserved [1415010000000000000000000000000000000000000000], CRC (4 bytes) [15090113bf3eef00000000]
[+] uploading 'u-boot.bin' (size 246572) to 0x80100000
[+] uploading 'uImage' (size 6974112) to 0x80a00000
[+] sending jump command: 0x6a425355, 0x80100000, 12
[+] jumping to address 0x80100000
[+] successfully transfered 3 files

3. Post-Exploit Access

After successful upload:

Device reboots automatically
SSH server is installed
Root password is reset to: gtvh4ckr

Important: Change the default password immediately after gaining access.

File Structure After Build

cuckoo_loader/
├── build.sh                 # Main build script
├── load_firmware.sh         # Exploit execution script
├── Readme.md               # Basic documentation
├── build/
│   ├── toolchain/          # ARM cross-compilation toolchain
│   ├── NestDFUAttack-master/  # Original exploit source
│   ├── x-loader/           # First stage bootloader source
│   ├── omap_loader/        # USB upload tool source
│   └── bin/                # Final built binaries
│       ├── host/
│       │   └── omap_loader # Host tool for USB upload
│       └── nest/
│           ├── x-load.bin  # First stage bootloader
│           ├── u-boot.bin  # U-Boot bootloader
│           └── uImage      # Linux kernel image
├── mods_linux/             # Linux kernel patches
└── mods_u-boot/            # U-Boot patches

Advanced Configuration

Custom Kernel Configuration

To modify kernel options:

cd build/NestDFUAttack-master/Dev/linux
make ARCH=arm menuconfig  # Requires ncurses-dev package

Rebuilding Individual Components

Rebuild just the kernel:

cd build/NestDFUAttack-master/Dev/linux
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- distclean
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- gtvhacker_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage

Rebuild just u-boot:

cd build/NestDFUAttack-master/Dev/u-boot
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- distclean
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- diamond
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi-

Known Limitations

Tested primarily on older Linux systems
USB device detection may be unreliable on some systems
Requires physical access to Nest device
May not work on all Nest thermostat revisions

Security Considerations

This exploit requires physical access to the device
Changes device firmware - potential for bricking
Installs SSH server with default credentials
Use at your own risk - author assumes no responsibility

Support

For issues not covered here:

Check the GitHub issues: https://github.com/ajb142/cuckoo_loader/issues
Original NestDFUAttack repository: https://github.com/exploiteers/NestDFUAttack
omap_loader repositories referenced in README

elecnix/cuckoo_loader on Ubuntu 25.10.md