AutoPYara
Automated, Cluster-Driven YARA Rule Generation
Automatically discover malware families and generate high-quality, tightly scoped YARA rules using probabilistic clustering and Bloom-filtered n-gram analysis.
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📌 Overview
AutoPYara is a Python framework for automated YARA rule generation from collections of malware samples. It combines:
- Variational Bayesian Gaussian Mixture Models (VBGMM)
- Augmented DBSCAN with centroid refinement
- Malicious/benign Bloom filter isolation
- Byte-level n-gram feature extraction
The result: cluster-aware, precision-engineered YARA signatures with minimal manual effort.
🧠 How it works
flowchart TD
A[Malware Samples] --> B[Byte n-gram Extraction]
B --> C["Bloom Filter Isolation<br/>(benign removal + malicious focus)"]
C --> D["Clustering Engine<br/>(VBGMM or Augmented DBSCAN)"]
D --> E[Cluster-Specific Signature Construction]
E --> F[High-Quality YARA Rules]
✨ Features
- Automated Clustering — group similar malware samples together automatically to create concise, targeted rules.
- Two Core Presets — the standard
AutoYara(VBGMM) approach, or the enhancedAutoPYara(Augmented DBSCAN) pipeline. - Built-in Bloom Filters — ships with pre-trained EMBER and AutoPYara filters to efficiently filter out benign n-grams.
- Multiple Output Formats — raw strings, compiled
yara-pythonobjects, oryaramodparsed objects. - Custom Training — train your own Bloom filters on proprietary datasets.
🚀 Installation
Requirements
- Python >= 3.9
- A Java Runtime Environment (JRE 11+) on
PATHor pointed to byJAVA_HOME. AutoPYara's clustering/rule-generation backend runs inside a JVM.pip installitself doesn't need Java, butAutoPYara()will raise a clear error the first time you construct it without one — install a JRE before you actually use the tool. On Debian/Ubuntu:sudo apt install default-jre.
pip install autopyara
Install from a local build instead
python -m build
pip install dist/autopyara-*.whl
Note on first run: the Bloom filter data (~600MB)
To keep the initial install lightweight, the package needs about 600MB of pre-trained Bloom filter data that isn't bundled in the distribution. You don't need to fetch this manually — the first time you import autopyara and the data is missing, it's downloaded automatically from the data-branch branch of this repository. To trigger it explicitly (e.g. to pre-warm a Docker image):
autopyara-download
⚡ Quick Start
Generating your first YARA rule is as simple as pointing the tool at a directory of malware samples.
from autopyara import AutoPYara
# 1. Initialize the tool
tool = AutoPYara()
# 2. Generate a rule using the AutoPYara preset
results = tool.generate(
input_files="/path/to/malware/directory",
preset="AutoPYara",
rule_name="my_custom_rule",
output_format="string"
)
# 3. Print the results
print(f"Discovered {results['k_clusters']} distinct malware clusters.")
print("\nGenerated YARA Rule:")
print(results['rule_string'])
⚙️ Core presets
preset="AutoYara" (Standard)
Algorithm: Variational Bayesian Gaussian Mixture Model (VBGMM)
Behavior: Automatically infers the number of clusters ($K$) probabilistically.
Best for: General-purpose rule generation where the structural diversity of the input directory is completely unknown.
preset="AutoPYara" (Enhanced)
Algorithm: Augmented DBSCAN combined with KMeans soft clustering
Behavior: Uses a custom Augmented DBSCAN to calculate $K$ prior to centroid optimization.
Best for: Producing more tightly bound rules for closely related malware families.
🛠 Advanced usage
Defining a custom $K$
If you want to manually force the algorithm to split your samples into a specific number of clusters, you can override the presets:
# Force exactly 4 clusters using the AutoPYara augmented pipeline
results = tool.generate(
input_files="/path/to/malware",
preset="AutoPYara",
augmented_target_k=4 # Forces the optimizer to find 4 clusters
)
Output formats
By default, AutoPYara returns a raw string. You can integrate it directly into existing analysis pipelines by requesting Python objects instead:
# Returns a compiled yara-python object ready for immediate scanning
results = tool.generate(
input_files="/path/to/malware",
output_format="yara-python"
)
compiled_rule = results["output"]
matches = compiled_rule.match("/path/to/suspicious/file.exe")
Supported formats: 'string', 'yara-python', and 'yaramod'.
Custom Bloom filters
generate() defaults to the built-in "ember" Bloom filters for both benign and malicious data. You can switch to the "autopyara" defaults, or provide absolute paths to your own retrained filters:
results = tool.generate(
input_files="/path/to/malware",
bloom_malicious="/absolute/path/to/custom/malicious_bloom",
bloom_benign="/absolute/path/to/custom/benign_bloom",
)
Training new Bloom filters
Train custom Bloom filters on your own proprietary benign or malicious datasets with train():
tool = AutoPYara()
# Extract 8-grams from a directory of benign software
tool.train(
input_dir="/path/to/benign/software",
output_dir="/path/to/save/new/bloom",
ngram_size=8
)
📚 Full API reference: generate()
| Parameter | Type | Default | Description |
|---|---|---|---|
input_files |
str | list |
Required | Path to input directory or list of sample file paths. |
preset |
str |
None |
'AutoYara' or 'AutoPYara'. Auto-configures the clustering pipeline. |
bloom_malicious |
str |
'ember' |
Built-in flag ('ember', 'autopyara') or path to custom malicious Bloom filters. |
bloom_benign |
str |
'ember' |
Built-in flag ('ember', 'autopyara') or path to custom benign Bloom filters. |
output_format |
str |
'string' |
'string', 'yara-python', or 'yaramod'. Determines output rule format. |
rule_name |
str |
'autoyara_rule' |
Base string used to name the generated rules. |
k_cluster |
int |
0 |
Hardcode $K$ for VBGMM. Do not use with preset="AutoPYara". |
augmented_target_k |
int |
None |
Hardcode target $K$ for the Augmented DBSCAN pipeline. |
verbose |
bool |
False |
Enable detailed logging during cluster generation. |
📖 Documentation
Full documentation lives at botacin-s-lab.github.io/AutoPYaraPyPI. It's intentionally basic for now — installation, quick start, and the API reference — with more material (including the accompanying paper, once published) landing there over time.
🧪 Development
pip install -e ".[test]"
pytest tests/
tests/test_core_helpers.py and tests/test_augmented_dbscan.py are pure-Python unit tests (no JVM/network needed). tests/test_smoke_generate.py runs the real pipeline end-to-end against small synthetic dummy files (not real malware) using the built-in Bloom filters.
See RELEASING.md for how versioning and PyPI publishing work.
🤝 Contributing
We're accepting contributions — if you run into an issue or have a fix, fork the repo, open a PR against main, and we'll take a look. PRs are automatically built and tested; once checks pass and a maintainer approves, it gets merged. main itself isn't open to direct pushes from anyone (including maintainers) — everything goes through review. See CONTRIBUTING.md for details.
License
MIT — see LICENSE.
Maintained by Mabon Ninan, Texas A&M University — ninanmm@tamu.edu
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