Download from vendor

wget http://vendor.com/firmware/update.bin

Extract from device via debug interface

UART console access

screen /dev/ttyUSB0 115200

Copy firmware partition

dd if=/dev/mtd0 of=/tmp/firmware.bin

Extract via network protocols

TFTP during boot

HTTP/FTP from device web interface

### Hardware Methods

UART access - Serial console connection JTAG/SWD - Debug interface for memory access SPI flash dump - Direct chip reading NAND/NOR dump - Flash memory extraction Chip-off - Physical chip removal and reading Logic analyzer - Protocol capture and analysis

## Use this skill when

- Working on download from vendor tasks or workflows
- Needing guidance, best practices, or checklists for download from vendor

## Do not use this skill when

- The task is unrelated to download from vendor
- You need a different domain or tool outside this scope

## Instructions

- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
- If detailed examples are required, open `resources/implementation-playbook.md`.

## Firmware Analysis Workflow

### Phase 1: Identification

Basic file identification

file firmware.bin binwalk firmware.bin

Entropy analysis (detect compression/encryption)

Binwalk v3: generates entropy PNG graph

binwalk --entropy firmware.bin binwalk -E firmware.bin # Short form

Identify embedded file systems and auto-extract

binwalk --extract firmware.bin binwalk -e firmware.bin # Short form

String analysis

strings -a firmware.bin | grep -i "password\|key\|secret"

### Phase 2: Extraction

Binwalk v3 recursive extraction (matryoshka mode)

binwalk --extract --matryoshka firmware.bin binwalk -eM firmware.bin # Short form

Extract to custom directory

binwalk -e -C ./extracted firmware.bin

Verbose output during recursive extraction

binwalk -eM --verbose firmware.bin

Manual extraction for specific formats

SquashFS

unsquashfs filesystem.squashfs

JFFS2

jefferson filesystem.jffs2 -d output/

UBIFS

ubireader_extract_images firmware.ubi

YAFFS

unyaffs filesystem.yaffs

Cramfs

cramfsck -x output/ filesystem.cramfs

### Phase 3: File System Analysis

Explore extracted filesystem

find . -name ".conf" -o -name ".cfg" find . -name "passwd" -o -name "shadow" find . -type f -executable

Find hardcoded credentials

grep -r "password" . grep -r "api_key" . grep -rn "BEGIN RSA PRIVATE KEY" .

Analyze web interface

find . -name ".cgi" -o -name ".php" -o -name "*.lua"

Check for vulnerable binaries

checksec --dir=./bin/

### Phase 4: Binary Analysis

Identify architecture

file bin/httpd readelf -h bin/httpd

Load in Ghidra with correct architecture

For ARM: specify ARM:LE:32:v7 or similar

For MIPS: specify MIPS:BE:32:default

Set up cross-compilation for testing

ARM

arm-linux-gnueabi-gcc exploit.c -o exploit

MIPS

mipsel-linux-gnu-gcc exploit.c -o exploit

## Common Vulnerability Classes

### Authentication Issues

Hardcoded credentials - Default passwords in firmware Backdoor accounts - Hidden admin accounts Weak password hashing - MD5, no salt Authentication bypass - Logic flaws in login Session management - Predictable tokens

### Command Injection

// Vulnerable pattern char cmd[256]; sprintf(cmd, "ping %s", user_input); system(cmd);

// Test payloads ; id | cat /etc/passwd whoami $(id)

### Memory Corruption

Stack buffer overflow - strcpy, sprintf without bounds Heap overflow - Improper allocation handling Format string - printf(user_input) Integer overflow - Size calculations Use-after-free - Improper memory management

### Information Disclosure

Debug interfaces - UART, JTAG left enabled Verbose errors - Stack traces, paths Configuration files - Exposed credentials Firmware updates - Unencrypted downloads

## Tool Proficiency

### Extraction Tools

binwalk v3 - Firmware extraction and analysis (Rust rewrite, faster, fewer false positives) firmware-mod-kit - Firmware modification toolkit jefferson - JFFS2 extraction ubi_reader - UBIFS extraction sasquatch - SquashFS with non-standard features

### Analysis Tools

Ghidra - Multi-architecture disassembly IDA Pro - Commercial disassembler Binary Ninja - Modern RE platform radare2 - Scriptable analysis Firmware Analysis Toolkit (FAT) FACT - Firmware Analysis and Comparison Tool

### Emulation

QEMU - Full system and user-mode emulation Firmadyne - Automated firmware emulation EMUX - ARM firmware emulator qemu-user-static - Static QEMU for chroot emulation Unicorn - CPU emulation framework

### Hardwar