Offensive Security Tool: msoffcrypto-tool

msoffcrypto-tool

msoffcrypto-tool (formerly ms-offcrypto-tool) by nolze, is a Python tool and library for decrypting encrypted MS Office files with password, intermediate key, or private key which generated its escrow key. It supports various MS Office file formats, including Word (MS-DOCX), Excel (MS-XLSX), and PowerPoint (MS-PPTX).

Installation

pip install msoffcrypto-tool

Examples

As CLI tool (with password)

msoffcrypto-tool encrypted.docx decrypted.docx -p Passw0rd

Password is prompted if you omit the password argument value:

$ msoffcrypto-tool encrypted.docx decrypted.docx -p

Password:

Test if the file is encrypted or not (exit code 0 or 1 is returned):

msoffcrypto-tool document.doc --test -v

As library

Password and more key types are supported with library functions.

Basic usage:

Basic usage (in-memory):

Advanced usage:

# Verify password before decryption (default: False)
# The ECMA-376 Agile/Standard crypto system allows one to know whether the supplied password is correct before actually decrypting the file
# Currently, the verify_password option is only meaningful for ECMA-376 Agile/Standard Encryption
file.load_key(password="Passw0rd", verify_password=True)

# Use private key
file.load_key(private_key=open("priv.pem", "rb"))

# Use intermediate key (secretKey)
file.load_key(secret_key=binascii.unhexlify("AE8C36E68B4BB9EA46E5544A5FDB6693875B2FDE1507CBC65C8BCF99E25C2562"))

# Check the HMAC of the data payload before decryption (default: False)
# Currently, the verify_integrity option is only meaningful for ECMA-376 Agile Encryption
file.decrypt(open("decrypted.docx", "wb"), verify_integrity=True)

MS-OFFCRYPTO specs

•  ECMA-376 (Agile Encryption/Standard Encryption)
  •  MS-DOCX (OOXML) (Word 2007-)
  •  MS-XLSX (OOXML) (Excel 2007-)
  •  MS-PPTX (OOXML) (PowerPoint 2007-)
•  Office Binary Document RC4 CryptoAPI
  •  MS-DOC (Word 2002, 2003, 2004)
  •  MS-XLS (Excel 2002, 2003, 2007, 2010) (experimental)
  •  MS-PPT (PowerPoint 2002, 2003, 2004) (partial, experimental)
•  Office Binary Document RC4
  •  MS-DOC (Word 97, 98, 2000)
  •  MS-XLS (Excel 97, 98, 2000) (experimental)
•  ECMA-376 (Extensible Encryption)
•  XOR Obfuscation
  •  MS-XLS (Excel 2002, 2003) (experimental)
  •  MS-DOC (Word 2002, 2003, 2004?)

Other

•  Word 95 Encryption (Word 95 and prior)
•  Excel 95 Encryption (Excel 95 and prior)
•  PowerPoint 95 Encryption (PowerPoint 95 and prior)

Tests

With coverage and pytest:

poetry install

poetry run coverage run -m pytest -v

Clone the repo from here: GitHub Link