# Lockfile injection research — Liran Tal

My 2019 research into malicious dependency sources hidden in npm and Yarn lockfiles, and the defenses and follow-on research it led to.

Canonical: https://lirantal.com/research/lockfile-injection

## A dependency change hiding in plain sight

In September 2019, I demonstrated how a pull request could redirect a dependency to attacker-controlled code through a lockfile. The package name and version could look familiar while its download source changed beneath the reviewer’s attention.

Large, generated diffs make this kind of change difficult to spot. The research examined how npm and Yarn treat lockfile entries as installation instructions, and why reviewing package.json alone does not establish the trustworthiness of an install.

*   [Read the original 2019 research ↗](https://snyk.io/blog/why-npm-lockfiles-can-be-a-security-blindspot-for-injecting-malicious-modules/)

## Turning the finding into a defense

I built lockfile-lint to make dependency-source checks repeatable in development and CI. It lets teams enforce policies such as HTTPS and approved registry hosts, so suspicious sources can be flagged automatically.

The tool addresses a particular trust boundary in dependency installation. It complements package review and vulnerability scanning; an allowed registry alone cannot guarantee that a package is safe.

*   [Explore lockfile-lint ↗](https://github.com/lirantal/lockfile-lint)

## From the original finding to Black Hat

GitLab researchers Dennis Appelt and Greg Johnson extended this work for “Picking Lockfiles: Attacking and Defending Your Supply Chain” at Black Hat Europe 2021. Their published notes explicitly credit my initial research.

They explored additional tampering techniques and extended the analysis to Ruby and Go, alongside Node.js. Their work also introduced defensive verification and tooling to automate lockfile tampering for security testing.

*   [Read GitLab’s research & acknowledgement ↗](https://gitlab.com/gitlab-com/gl-security/security-operations/redteam/redteam-public/resources/red-team-tech-notes/-/tree/master/blackhat-eu-2021-picking-lockfiles)
*   [Watch the Black Hat presentation ↗](https://www.youtube.com/watch?v=UkWJeqb8BZk)

## At a glance

Original publication

September 24, 2019

Ecosystems studied

npm & Yarn

Defensive tool

lockfile-lint

Follow-on presentation

Black Hat Europe 2021

[Sources & attribution ↓](#sources)

## Sources & attribution

*   [Original research · Liran Tal, Snyk, 2019 ↗](https://snyk.io/blog/why-npm-lockfiles-can-be-a-security-blindspot-for-injecting-malicious-modules/)
*   [Black Hat EU 2021 research · Dennis Appelt & Greg Johnson, GitLab ↗](https://gitlab.com/gitlab-com/gl-security/security-operations/redteam/redteam-public/resources/red-team-tech-notes/-/tree/master/blackhat-eu-2021-picking-lockfiles)
*   [Defensive implementation · lockfile-lint ↗](https://github.com/lirantal/lockfile-lint)