Packj is an open-source software supply-chain security tool that flags malicious, vulnerable, abandoned, and typo-squatting dependencies before they reach production, built for developers and DevOps and DevSecOps teams who vet npm, PyPI, RubyGems, Cargo, Packagist, and NuGet packages.

What it is

Packj is a Python tool, licensed AGPL-3.0, that analyses open-source dependencies for risk. It detects malicious, vulnerable, abandoned, typo-squatting, and other "risky" packages from popular open-source package registries, including NPM, RubyGems, and PyPI. It works through deep static and dynamic code analysis and sandboxing, and it can be customized to minimize noise by turning alerts off according to a chosen threat model. The project began as a PhD research project and is currently developed under various government grants, with a lead team of cybersecurity researchers from academia and industry.

The concrete problem it solves is behavioral blind spots in dependency scanning. As the README states, existing CVE scanners assume code is benign and do not analyze its behavior, so a package that runs malicious install scripts or exfiltrates data can pass a vulnerability scan untouched. Packj replaces that assumption with dynamic analysis and sandboxed execution, and its authors report over 70 malicious PyPI and RubyGems packages found. It lives in the Python ecosystem and ships as a command-line tool, a Docker image, and a GitHub Action.

Key capabilities

• Flags malicious, vulnerable, abandoned, and typo-squatting packages across NPM, PyPI, Cargo, Rubygems, and Packagist registries, with Rust and PHP support marked work in progress.
• Performs deep static and dynamic code analysis and sandboxing of packages, reflected in the dynamic-analysis, sandboxing, and malware-analysis topics.
• Runs as a pull-request audit with ossillate-inc/[email protected], taking DEPENDENCY_FILES: pypi:requirements.txt,npm:package.json,rubygems:Gemfile and a REPO_TOKEN.
• Ships as the Docker image ossillate/packj:latest, runnable as docker run -v /tmp:/tmp/packj -it ossillate/packj:latest --help, with Podman supported for containerized, isolated runs.
• Vets local, unpublished NPM and PyPI packages in addition to packages published to a registry.
• Allows customization to turn off alerts per threat model, reducing false-positive noise.
• Exposes a command-line entry point from a source checkout via python3 main.py --help.

Who uses it and how

• Development teams that audit dependency changes inside pull requests, wiring the GitHub Action into their CI so every manifest change is checked against the configured DEPENDENCY_FILES.
• DevSecOps and security engineers triaging supply-chain risk across several language ecosystems at once, using one tool instead of separate per-registry checks.
• Python, JavaScript, and Ruby teams whose dependency files are requirements.txt, package.json, and Gemfile.
• Researchers and practitioners following the project's presentations from PyCon, the Open Source Summit, and BlackHAT.
• Individual developers evaluating it quickly through the Docker image before committing to a CI integration.

Getting started

The README calls the Docker image the recommended and quickest way to try Packj: docker run -v /tmp:/tmp/packj -it ossillate/packj:latest --help. Alternatives are the GitHub Action ossillate-inc/[email protected], or cloning the repository and running bundle install && pip3 install -r requirements.txt followed by python3 main.py --help.

How it compares

The README positions Packj against existing CVE scanners, which it says assume code is benign and do not analyze its behavior; Packj instead applies static and dynamic analysis and sandboxing to catch malicious packages that a vulnerability database would miss. No other comparable tool is named in the facts supplied for this registry, so on this page it stands alone. There is no list of paid products it replaces, and no licence, self-hosting, data-ownership, or cost comparison against commercial offerings is supported by the facts.

When to use it — and when not to

A self-hoster must operate either the Docker or Podman container or a source checkout with Ruby Bundler and Python dependencies installed, and must accept the obligations of the AGPL-3.0 licence. The project is marked beta, its self-hosted webserver and several integrations were still listed as coming, Docker registry scanning is not supported, and Rust and PHP support is work in progress. Teams that want a turnkey hosted service, or that need Docker image vetting or stable non-beta interfaces, should not pick it yet.

- name: Packj Security Audit
  uses: ossillate-inc/[email protected]
  with:
    # TODO: replace with your dependency files in the repo
    DEPENDENCY_FILES: pypi:requirements.txt,npm:package.json,rubygems:Gemfile
    REPO_TOKEN: ${{ secrets.GITHUB_TOKEN }}

docker run -v /tmp:/tmp/packj -it ossillate/packj:latest --help

git clone https://github.com/ossillate-inc/packj.git && cd packj

bundle install && pip3 install -r requirements.txt

python3 main.py --help 

$ docker run -v /tmp:/tmp/packj -it ossillate/packj:latest audit --trace -p npm:browserify

[+] Fetching 'browserify' from npm..........PASS [ver 17.0.0]
[+]    Checking package description.........PASS [browser-side require() the node way]
[+]    Checking release history.............PASS [484 version(s)]
[+] Checking version........................RISK [702 days old]
[+]    Checking release time gap............PASS [68 days since last release]
[+] Checking author.........................PASS [[email protected]]
[+]    Checking email/domain validity.......RISK [expired author email domain]
[+] Checking readme.........................PASS [26838 bytes]
[+] Checking homepage.......................PASS [https://github.com/browserify/browserify#readme]
[+] Checking downloads......................PASS [2M weekly]
[+] Checking repo URL.......................PASS [https://github.com/browserify/browserify]
[+]    Checking repo data...................PASS [stars: 14189, forks: 1244]
[+]    Checking if repo is a forked copy....PASS [original, not forked]
[+]    Checking repo description............PASS [browser-side require() the node.js way]
[+]    Checking repo activity...............PASS [commits: 2290, contributors: 207, tags: 413]
[+] Checking for CVEs.......................PASS [none found]
[+] Checking dependencies...................RISK [48 found]
[+] Downloading package from npm............PASS [163.83 KB]
[+] Analyzing code..........................RISK [needs 3 perm(s): decode,codegen,file]
[+] Checking files/funcs....................PASS [429 files (383 .js), 744 funcs, LoC: 9.7K]
[+] Installing package and tracing code.....PASS [found 5 process,1130 files,22 network syscalls]
=============================================
[+] 5 risk(s) found, package is undesirable!
=> Complete report: /tmp/packj_54rbjhgm/report_npm-browserify-17.0.0_hlr1rhcz.json
{
    "undesirable": [
        "old package: 702 days old",
        "invalid or no author email: expired author email domain",
        "generates new code at runtime",
        "reads files and dirs",
        "forks or exits OS processes",
    ]
}

$ python3 main.py sandbox gem install overcommit

Fetching: overcommit-0.59.1.gem (100%)
Install hooks by running `overcommit