Dependency confusion occurs when a build system or continuous integration pipeline resolves a package name to a public registry artifact instead of the intended private package, allowing an attacker to publish a malicious package and have CI systems install it automatically. Alex Birsan, security researcher, demonstrated this technique and published technical findings that exposed how common package managers and default CI configurations can be abused. The root causes are predictable: unscoped or ambiguous package names, default registry resolution behavior in npm pip and NuGet, and CI environments that lack enforced private-registry authentication or registry locks. The consequence is not only execution of attacker code during builds but also exfiltration of CI secrets, compromise of build artifacts, and downstream supply-chain infection that affects customers and partners.
Detection strategies
Detecting dependency confusion requires visibility into what package sources CI actually contacts. Observability can be improved by logging all registry fetches and comparing resolved package origins against an expected private registry allowlist. Continuous monitoring of CI network traffic and artifact hashes can reveal unexpected connections to public registries or changes in package content. Security teams can also use automated scanning tools that flag packages whose published metadata does not match the organization’s internal packages. Guidance from Microsoft Security Response Center at Microsoft emphasizes validating registry configuration in automated builds and watching for unexpected downloads as early detection signals.
Prevention strategies
Prevention is layered: enforce use of scoped or namespaced packages and configure CI to authenticate to private registries via pinned credentials or tokens so public registries are not consulted. Package manager configuration files such as npmrc or pip configuration must explicitly set the private index URL and reject fallback to public registries. Maintain an internal mirror or proxy for external dependencies so CI never resolves directly to public endpoints. Generating and verifying an SBOM for builds and using cryptographic signatures on packages reduce risk by enabling provenance checks. OWASP recommends incorporating supply-chain verification practices into build pipelines to ensure only trusted artifacts are permitted. Operationally, restricting CI secret scope and limiting outbound network access during builds further reduces the impact of any unexpected package. Culturally, organizations with distributed development teams and heavy open-source use should prioritize education about naming conventions and registry hygiene since human error in package naming is often the initial vector. Sustained attention to configuration, monitoring, and provenance creates practical defenses against dependency confusion in CI.