Visualize and force decode YARA and regex matches found in a file or byte stream. With colors. Lots of colors.
Project description
THE YARALYZER
Visually inspect all of the regex matches (and their sexier, more cloak and dagger cousins, the YARA matches) found in binary data and/or text. See what happens when you force various character encodings upon those matched bytes. With colors.
Quick Start
pipx install yaralyzer
# Scan against YARA definitions in a file:
yaralyze --yara-rules /secret/vault/sigmunds_malware_rules.yara lacan_buys_the_dip.pdf
# Scan against an arbitrary regular expression:
yaralyze --regex-pattern 'good and evil.*of\s+\w+byte' the_crypto_archipelago.exe
What It Do
- See the actual bytes your YARA rules are matching. No more digging around copy/pasting the start positions reported by YARA into your favorite hex editor. Displays both the bytes matched by YARA as well as a configurable number of bytes before and after each match in hexadecimal and "raw" python string representation.
- Display bytes matching arbitrary regular expressions. If, say, you were trying to determine whether there's a regular expression hidden somewhere in the file you could scan for the pattern
'/.+/'
and immediately get a window into all the bytes in the file that live between front slashes. Same story for quotes, BOMs, etc. Any regex YARA can handle is supported so sky's the limit. - Detect the possible encodings of each set of matched bytes. The
chardet
library is a sophisticated library for guessing character encodings and it is leveraged here. - Display the result of forcing various character encodings upon the matched areas. Several default character encodings will be forcibly attempted in the region around the match.
chardet
will also be leveraged to see if the bytes fit the pattern of any known encoding. Ifchardet
is confident enough (configurable), an attempt at decoding the bytes using that encoding will be displayed. - Export the matched regions/decodings to SVG, HTML, and colored text files. Show off your ASCII art.
Why It Do
The Yaralyzer's functionality was extracted from The Pdfalyzer when it became apparent that visualizing and decoding pattern matches in binaries had more utility than just in a PDF analysis tool.
YARA, for those who are unaware[^1], is branded as a malware analysis/alerting tool but it's actually both a lot more and a lot less than that. One way to think about it is that YARA is a regular expression matching engine on steroids. It can locate regex matches in binaries like any regex engine but it can also do far wilder things like combine regexes in logical groups, compare regexes against all 256 XORed versions of a binary, and more. Maybe most importantly it provides a standard text based format for people to [i]share[/i] their 'roided regexes. All these features are particularly useful when analyzing or reverse engineering software.
But... that's also all it does. Everything else is up to the user. YARA's just a match enginer. I found myself a bit frustrated trying to use YARA to look at all the matches of a few critical patterns:
- Bytes between escaped quotes (
\".+\"
and\'.+\'
) - Bytes between front slashes (
/.+/
). Front slashes demarcate a regular expression in many implementations and I was trying to see if any of the bytes matching this pattern were actually regexes.
YARA just tells you the byte position and the matched string but it can't tell you whether those bytes are UTF-8, UTF-16, Latin-1, etc. etc. (or none of the above). I also found myself wanting to understand what was going in the region of the matches and not just in the matches. In other words I wanted to scope the bytes immediately before and after whatever got matched.
Enter The Yaralyzer, which lets you quickly scan the regions around matches while also showing you what those regions would look like if they were forced into various character encodings.
Installation
Install it with pipx
or pip3
. pipx
is a marginally better solution as it guarantees any packages installed with it will be isolated from the rest of your local python environment. Of course if you don't really have a local python environment this is a moot point and you can feel free to install with pip
/pip3
.
pipx install yaralyzer
Usage
Run yaralyzer -h
to see the command line options (screenshot below).
Configuration
If you place a filed called .yaralyzer
in your home dir or the current dir environment variables specified in that .yaralyzer
file will be added to the environment each time yaralyzer is invoked, permanently configuring various command line options so you can avoid typing them over and over. See the example file .yaralyzer.example
to see which options can be configured this way.
As A Library
Yaralyzer
is the main class. It has a variety of constructors supporting:
- Precompiled YARA rules
- Creating a YARA rule from a string
- Loading YARA rules from files
- Loading YARA rules from all
.yara
file in a directory - Scanning
bytes
- Scanning a file
Should you want to iterate over the BytesMatch
(like a re.Match
object for a YARA match) and BytesDecoder
(tracks decoding attempt stats) objects returned by The Yaralyzer, you can do so like this:
from yaralyzer.yaralyzer import Yaralyzer
yaralyzer = Yaralyzer.for_rules_files(['/secret/rule.yara'], 'lacan_buys_the_dip.pdf')
for bytes_match, bytes_decoder in yaralyzer.match_iterator():
do_stuff()
Example Output
The Yaralyzer can export visualizations to HTML, ANSI colored text, and SVG vector images using the file export functionality that comes with Rich. SVGs can be turned into png
format images with a tool like inkscape
or cairosvg
(Inkscape works a lot better in our experience).
PyPi Users: If you are reading this document on PyPi be aware that it renders a lot better over on GitHub. Pretty pictures, footnotes that work, etc.
Raw YARA match result:
Display hex, raw python string, and various attempted decodings of both the match and the bytes before and after the match (configurable):
Bonus: see what chardet.detect()
thinks about the likelihood your bytes are in a given encoding/language:
[^1]: As I was until recently.
Project details
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
Built Distribution
Hashes for yaralyzer-0.3.2-py3-none-any.whl
Algorithm | Hash digest | |
---|---|---|
SHA256 | fc677ab8b1e4bd5be11b07cd0b662bd12c14d8b649107b6f99a3f26ad0101af9 |
|
MD5 | 86295beacd6a39d10145f4846f610bfa |
|
BLAKE2b-256 | b5ea76a7f472191123e1fcb2bdd5ee8196a6842f10d732401fc1f9e26d157759 |