# msoffcrypto-tool

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msoffcrypto-tool is a Python tool and library for decrypting and encrypting MS Office files using a password or other keys.

## Contents

* [Installation](#installation)
* [Examples](#examples)
* [Supported encryption methods](#supported-encryption-methods)
* [Tests](#tests)
* [Todo](#todo)
* [Resources](#resources)
* [Use cases and mentions](#use-cases-and-mentions)
* [Contributors](#contributors)
* [Credits](#credits)

## Installation

```
pip install msoffcrypto-tool
```

## Examples

### As CLI tool (with password)

#### Decryption

Specify the password with `-p` flag:

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

Password is prompted if you omit the password argument value:

```bash
$ msoffcrypto-tool encrypted.docx decrypted.docx -p
Password:
```

To check if the file is encrypted or not, use `-t` flag:

```
msoffcrypto-tool document.doc --test -v
```

It returns `1` if the file is encrypted, `0` if not.

#### Encryption (OOXML only, experimental)

> [!IMPORTANT]
> Encryption feature is experimental. Please use it at your own risk.

To password-protect a document, use `-e` flag along with `-p` flag:

```
msoffcrypto-tool -e -p Passw0rd plain.docx encrypted.docx
```

### As library

Password and more key types are supported with library functions.

#### Decryption

Basic usage:

```python
import msoffcrypto

encrypted = open("encrypted.docx", "rb")
file = msoffcrypto.OfficeFile(encrypted)

file.load_key(password="Passw0rd")  # Use password

with open("decrypted.docx", "wb") as f:
    file.decrypt(f)

encrypted.close()
```

In-memory:

```python
import msoffcrypto
import io
import pandas as pd

decrypted = io.BytesIO()

with open("encrypted.xlsx", "rb") as f:
    file = msoffcrypto.OfficeFile(f)
    file.load_key(password="Passw0rd")  # Use password
    file.decrypt(decrypted)

df = pd.read_excel(decrypted)
print(df)
```

Advanced usage:

```python
# 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)
```

Supported key types are

- Passwords
- Intermediate keys (optional)
- Private keys used for generating escrow keys (escrow certificates) (optional)

See also ["Backdooring MS Office documents with secret master keys"](https://web.archive.org/web/20171008075059/http://secuinside.com/archive/2015/2015-1-9.pdf) for more information on the key types.

#### Encryption (OOXML only, experimental)

> [!IMPORTANT]
> Encryption feature is experimental. Please use it at your own risk.

Basic usage:

```python
from msoffcrypto.format.ooxml import OOXMLFile

plain = open("plain.docx", "rb")
file = OOXMLFile(plain)

with open("encrypted.docx", "wb") as f:
    file.encrypt("Passw0rd", f)

plain.close()
```

In-memory:

```python
from msoffcrypto.format.ooxml import OOXMLFile
import io

encrypted = io.BytesIO()

with open("plain.xlsx", "rb") as f:
    file = OOXMLFile(f)
    file.encrypt("Passw0rd", encrypted)

# Do stuff with encrypted buffer; it contains an OLE container with an encrypted stream
...
```

## Supported encryption methods

### MS-OFFCRYPTO specs

* [x] ECMA-376 (Agile Encryption/Standard Encryption)
  * [x] MS-DOCX (OOXML) (Word 2007-)
  * [x] MS-XLSX (OOXML) (Excel 2007-)
  * [x] MS-PPTX (OOXML) (PowerPoint 2007-)
* [x] Office Binary Document RC4 CryptoAPI
  * [x] MS-DOC (Word 2002, 2003, 2004)
  * [x] MS-XLS ([Excel 2002, 2003, 2007, 2010](https://learn.microsoft.com/en-us/openspecs/office_file_formats/ms-xls/a3ad4e36-ab66-426c-ba91-b84433312068#Appendix_A_22)) (experimental)
  * [x] MS-PPT (PowerPoint 2002, 2003, 2004) (partial, experimental)
* [x] Office Binary Document RC4
  * [x] MS-DOC (Word 97, 98, 2000)
  * [x] MS-XLS (Excel 97, 98, 2000) (experimental)
* [ ] ECMA-376 (Extensible Encryption)
* [x] XOR Obfuscation
  * [x] MS-XLS ([Excel 2002, 2003](https://learn.microsoft.com/en-us/openspecs/office_file_formats/ms-xls/a3ad4e36-ab66-426c-ba91-b84433312068#Appendix_A_21)) (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)

PRs are welcome!

## Tests

With [coverage](https://github.com/nedbat/coveragepy) and [pytest](https://pytest.org/):

```
poetry install
poetry run coverage run -m pytest -v
```

## Todo

* [x] Add tests
* [x] Support decryption with passwords
* [x] Support older encryption schemes
* [x] Add function-level tests
* [x] Add API documents
* [x] Publish to PyPI
* [x] Add decryption tests for various file formats
* [x] Integrate with more comprehensive projects handling MS Office files (such as [oletools](https://github.com/decalage2/oletools/)?) if possible
* [x] Add the password prompt mode for CLI
* [x] Improve error types (v4.12.0)
* [ ] Add type hints
* [ ] Introduce something like `ctypes.Structure`
* [x] Support OOXML encryption
* [ ] Support other encryption
* [ ] Isolate parser
* [ ] Redesign APIs (v6.0.0)

## Resources

* "Backdooring MS Office documents with secret master keys" [http://secuinside.com/archive/2015/2015-1-9.pdf](https://web.archive.org/web/20171008075059/http://secuinside.com/archive/2015/2015-1-9.pdf)
* Technical Documents <https://msdn.microsoft.com/en-us/library/cc313105.aspx>
  * [MS-OFFCRYPTO] Agile Encryption <https://msdn.microsoft.com/en-us/library/dd949735(v=office.12).aspx>
* [MS-OFFDI] Microsoft Office File Format Documentation Introduction <https://learn.microsoft.com/en-us/openspecs/office_file_formats/ms-offdi/24ed256c-eb5b-494e-b4f6-fb696ad2b4dc>
* LibreOffice/core <https://github.com/LibreOffice/core>
* LibreOffice/mso-dumper <https://github.com/LibreOffice/mso-dumper>
* wvDecrypt <http://www.skynet.ie/~caolan/Packages/wvDecrypt.html>
* Microsoft Office password protection - Wikipedia <https://en.wikipedia.org/wiki/Microsoft_Office_password_protection#History_of_Microsoft_Encryption_password>
* office2john.py <https://github.com/magnumripper/JohnTheRipper/blob/bleeding-jumbo/run/office2john.py>

## Alternatives

* herumi/msoffice <https://github.com/herumi/msoffice>
* DocRecrypt <https://blogs.technet.microsoft.com/office_resource_kit/2013/01/23/now-you-can-reset-or-remove-a-password-from-a-word-excel-or-powerpoint-filewith-office-2013/>
* Apache POI - the Java API for Microsoft Documents <https://poi.apache.org/>

## Use cases and mentions

### General

* <https://repology.org/project/python:msoffcrypto-tool/versions> (kudos to maintainers!)
<!-- * <https://checkroth.com/unlocking-password-protected-files.html> (outdated) -->

### Corporate

* Workato <https://docs.workato.com/connectors/python.html#supported-features> <!-- https://web.archive.org/web/20240525062245/https://docs.workato.com/connectors/python.html#supported-features -->
* Check Point <https://www.checkpoint.com/about-us/copyright-and-trademarks/> <!-- https://web.archive.org/web/20230326071230/https://www.checkpoint.com/about-us/copyright-and-trademarks/ -->

### Malware/maldoc analysis

* <https://github.com/jbremer/sflock/commit/3f6a96abe1dbb4405e4fb7fd0d16863f634b09fb>
* <https://isc.sans.edu/forums/diary/Video+Analyzing+Encrypted+Malicious+Office+Documents/24572/>

### CTF

* <https://github.com/shombo/cyberstakes-writeps-2018/tree/master/word_up>
* <https://github.com/willi123yao/Cyberthon2020_Writeups/blob/master/csit/Lost_Magic>

### In other languages

* <https://github.com/dtjohnson/xlsx-populate>
* <https://github.com/opendocument-app/OpenDocument.core/blob/233663b039/src/internal/ooxml/ooxml_crypto.h>
* <https://github.com/jaydadhania08/PHPDecryptXLSXWithPassword>
* <https://github.com/epicentre-msf/rpxl>

### In publications

* [Excel、データ整理＆分析、画像処理の自動化ワザを完全網羅！ 超速Python仕事術大全](https://books.google.co.jp/books?id=TBdVEAAAQBAJ&q=msoffcrypto) (伊沢剛, 2022)
* ["Analyse de documents malveillants en 2021"](https://twitter.com/decalage2/status/1435255507846053889), MISC Hors-série N° 24, "Reverse engineering : apprenez à analyser des binaires" (Lagadec Philippe, 2021)
* [シゴトがはかどる Python自動処理の教科書](https://books.google.co.jp/books?id=XEYUEAAAQBAJ&q=msoffcrypto) (クジラ飛行机, 2020)

## Contributors

* <https://github.com/nolze/msoffcrypto-tool/graphs/contributors>

## Credits

* The sample file for XOR Obfuscation is from: <https://github.com/openwall/john-samples/tree/main/Office/Office_Secrets>