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.
## Firmware Analysis Workflow
### Phase 1: Identification
```bash
# 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
# 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)
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