# base64dump.py
# Extract and decode Base64-encoded strings from files
# FOR610 Labs: 3.4, 4.5 | Sections: 3, 4 | Author: Didier Stevens
# Docs: https://docs.remnux.org/discover-the-tools/examine+static+properties/deobfuscation

% base64, decoding, didier-stevens

# Basic usage
base64dump.py file.txt

# Suppress default output
base64dump.py file.ps1 -n 10

# Select specific item
base64dump.py file.ps1 -s 2 -d


# --- Recipes (multi-tool chains) ---

# >> Extract Base64 PowerShell from Office Macro
# List streams — find macro (M) and data streams
oledump.py <document>
# Extract VBA source to understand what the macro does
oledump.py <document> -s <macro_stream> -v
# Scan data stream for Base64 strings
oledump.py <document> -s <data_stream> -d | base64dump.py -n 10
# Decode the longest Base64 hit to file
oledump.py <document> -s <data_stream> -d | base64dump.py -s 1 -d > payload.ps1

# >> Decode Base64 + Gzip Payload
# Find Base64 strings in the script
base64dump.py <script.ps1> -n 10
# Decode Base64 and decompress gzip in one chain
base64dump.py <script.ps1> -s <selection> -d | gunzip > decoded.ps1

# >> Decode Base64 + XOR Shellcode
# Find Base64 strings
base64dump.py <script.ps1> -n 10
# Decode Base64, then XOR with key
base64dump.py <script.ps1> -s <selection> -d | translate.py 'byte ^ <key>' > shellcode.bin

# >> Full Office Macro Decode Chain
# Step 1: List streams and extract VBA
oledump.py <document>
oledump.py <document> -s <macro_stream> -v
# Step 2: Extract Base64 from data stream
oledump.py <document> -s <data_stream> -d | base64dump.py -s 1 -d > stage1.ps1
# Step 3: Decode second Base64 layer + decompress
base64dump.py stage1.ps1 -s 3 -d | gunzip > stage2.ps1
# Step 4: XOR decode the shellcode
base64dump.py stage2.ps1 -s 2 -d | translate.py 'byte ^ 35' > shellcode.bin
# Step 5: Emulate the shellcode
scdbgc /f shellcode.bin /s -1