Didier Stevens

Saturday 16 February 2019

Overview of Content Published in January

Filed under: Announcement — Didier Stevens @ 7:46

Here is an overview of content I published in January:

Blog posts:

YouTube videos:

Videoblog posts:

SANS ISC Diary entries:

Saturday 26 January 2019

Update: msoffcrypto-crack.py Version 0.0.3

Filed under: Encryption,My Software,Update — Didier Stevens @ 13:44

This is a bug fix update: for agile encryption, Python module msoffcrypto does not throw an exception in method load_key when an invalid password is provided. It throws an exception when an attempt is made to decrypt the file.

I added a call to method decrypt to handle this case.

msoffcrypto-crack_V0_0_3.zip (https)
MD5: 45BAB81D744DA62182EC58A8F2E05BFE
SHA256: CF9DE02C72C07C07786BE09551CD17F6DBB83BCEF2A1C5435E06A695D7C6770E

Monday 7 January 2019

Update: msoffcrypto-crack.py Version 0.0.2

Filed under: Encryption,My Software,Update — Didier Stevens @ 0:00

In this update of msoffcrypto-crack.py, two new options were added:

-e takes a text file and extracts all words from this text file to be used in the dictionary attack. Words are strings delimited by space characters. Words between single or double quotes, and words after string “password” are put at the beginning of the list for the dictionary attack.

The idea for option -e, is that you give it the content of an email message that contains the password of the encrypted attachment(s).

-c takes the password to decrypt the document. You use this option after the password was recovered (with option -p or -e for example), and need to run the tool again to decrypt the document. You can run the password cracking each time when you need to decrypt the document, but if this takes too long, then you just run it once and from then on provide the recovered password with option -c.

Password VelvetSweatshop was added to the embedded password list.

msoffcrypto-crack_V0_0_2.zip (https)
MD5: 010B7FA68FCF9CE84427815EFDFE1C42
SHA256: 6B368E40EEE8A907D444A49963B37F456A3645991201CE06F0E46A0F2E188A74

Tuesday 1 January 2019

Overview of Content Published in December

Filed under: Announcement — Didier Stevens @ 0:00

Here is an overview of content I published in December:

Blog posts:

YouTube videos:

Videoblog posts:

SANS ISC Diary entries:

Monday 31 December 2018

New Tool: msoffcrypto-crack.py

Filed under: Encryption,maldoc,My Software — Didier Stevens @ 0:00

This is a new tool to recover the password of encrypted MS Office documents. I quickly put together this script to help with the analysis of encrypted, malicious documents.

This tool relies completely on Python module msoffcrypto to decrypt MS Office documents.

Since this is a Python tool based on a Python library, don’t except fast password recovery. This is more a convenience program.

It can recover passwords using a build-in password list, or you can provide your own list via option -p.

The tool can also decrypt the encrypted MS Office document if the password is recovered: used option -o to achieve this. Otherwise, the tool just displays the recovered password.

Like many of my tools, it can take its input from stdin and provide the decrypted document via stdout.

It’s developed with Python 2, and also tested on Python 3.

Read the man page for all the details: option -m.

msoffcrypto-crack_V0_0_1.zip (https)
MD5: F67060E0DE62727A1A69D0FD6F39013A
SHA256: 1466B94B56595BA0B91F0A2606F699E1D737E964F3F1A4DFDF7EAA47843DD063

Sunday 30 December 2018

Update: format-bytes.py Version 0.0.7

Filed under: My Software,Update — Didier Stevens @ 0:00

In this update, I added support for “run-length encoded” ASCII dump (-A), and X and S representation for strings:

format-bytes_V0_0_7.zip (https)
MD5: 58D3380B48593B3497AD04ACB1719CF3
SHA256: 8E07C1462AE88416CF8D5218A70BCFAE34F89B284684BFD0AC6B943A39E3CA8E

Saturday 29 December 2018

New Tool: SimpleEncoder

Filed under: 010 Editor,My Software — Didier Stevens @ 0:00

I needed a 010 Editor script to do ROT-47 encoding. The script I developed supports different types of simple encodings (including ROT-47):

With custom shift encoding, you choose the shift value by providing a number in a second input dialog. This number can be negative to shift the characters to the left in stead of to the right.µ

FYI: I submitted this script to 010 Editor’s repository.

SimpleEncoder_V1_0.zip (https)
MD5: 02C7BA20D8BF9EB965B3957BE8D26094
SHA256: 7C98B404F49F5E22A8A052AB4E100BF4ABCE37F39518293FC697D21C1D36A4F3

Friday 28 December 2018

Update: numbers-to-string.py Version 0.0.7

Filed under: My Software,Update — Didier Stevens @ 10:58

In this update, I added option -T. This is an alternative for option -t (table for number to character conversion). In stead of providing the full table with option -t, now you can provide a partial table with option -T, provided the table is present in the input.

This is often the case in DOSfuscated scripts:

In this example, the table starts with MkBMMM. Hence I use option -T MkBMMM, in stead of option -t with the full table: -t MkBMMMdkGLKIEzzjzlJJanhzSNf7,Y9x@bm(/5Hqo6 +8wri)$;uv{-QtgOUP}C:\VDFW.=y’AsRe0cp

numbers-to-string_v0_0_7.zip (https)
MD5: C23E49A24B54365F469BB35CCDA12701
SHA256: 3E9E7DF84359BEB4A054FC82E73C3E94219FC85E462FFBE3676C16E115F61AB3

Thursday 27 December 2018

Update: XORSearch Version 1.11.2

Filed under: My Software,Update — Didier Stevens @ 0:00

This update for XORSearch brings new features and bug fixes.

Starting with this version, XORSearch accepts input from stdin. Use filename – to read data from stdin:

Option -S will print out all strings found using all decoders supported by XORSearch. Strings are sequences of printable characters, ASCII and UNICODE, at least 4 characters long.

As option -S brings many of the functionalities of XORStrings to XORSearch, I’m no longer developing XORStrings.

Last new option is -r. You can use option -r to reverse the file before searching.

I’m also including more compiled versions (look inside the ZIP file).

XORSearch_V1_11_2.zip (https)
MD5: 2B76F6C730BAC6324E92A731F42FEB74
SHA256: 4206B843AC2B9417A85A4B5381023EC4613C5B5095A6A0A19A072C21C66DE93F

Wednesday 19 December 2018

Update:oledump.py Version 0.0.40

Filed under: My Software,Update — Didier Stevens @ 0:00

This new version adds option –password to use a different password than infected for samples inside password protected ZIP files.

And plugin_biff adds support for MS Excel 4.0 macros:

oledump_V0_0_40.zip (https)
MD5: 4013CC3A01D4CAE481EAA099A080B07F
SHA256: C5EC0B7B1EFA69D9EB6572F61D866ECEA7952FEADA06943377F8178C7A252E70

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