appsignalnpm
Advisory published Updated
appsignal is a confirmed malicious npm package (MAL-2026-12512) that steals credentials and exfiltrates sensitive data (malicious version 9999.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in appsignal (npm)
What this malware does
Package name appsignal shadows the legitimate @appsignal/* scope and is published at version 9999.0.0, a version-number pattern used to outrank private/internal dependencies during resolution. A preinstall script runs automatically on npm install and issues an HTTP GET to the hardcoded bare-IP endpoint http://75.119.137.232:31337/depconfuse, carrying the installer's os.hostname(), os.userInfo().username, process.cwd(), npm_config_registry, and CI repository-slug environment variables (GITHUB_REPOSITORY, CI_PROJECT_PATH, BUILD_REPOSITORY_NAME, BITBUCKET_REPO_FULL_NAME, TRAVIS_REPO_SLUG, DRONE_REPO, BUILDKITE_PIPELINE_SLUG, CIRCLE_PROJECT_REPONAME, JOB_NAME) as query parameters. The endpoint path /depconfuse, the bare-IP destination, the 9999.0.0 version, and the shadowing of an established scope indicate a dependency-confusion reconnaissance probe designed to identify internal build systems that resolve the public name over an intended private package.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for appsignal (version 9999.0.0).
If you installed it — respond
appsignal is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If appsignal was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks appsignal-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.