stellarfixnpm
Advisory published Updated
stellarfix is a confirmed malicious npm package (MAL-2026-12216) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.0, 1.0.3, 1.0.4). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in stellarfix (npm)
What this malware does
stellarfix ships a.NET Windows executable at bin/stellarfn.exe and a postinstall.js that enumerates bin/*.exe and unconditionally launches the first one via execFileSync during npm install. The package.json declares scripts.postinstall=node postinstall.js, so the binary runs automatically on any Windows installer. The bundled binary contains class and P/Invoke symbols consistent with a full remote-access trojan: a ClientSocket/ConnectServer C2 channel with AES-encrypted traffic, an XLogger module using SetWindowsHookEx / LowLevelKeyboardProc / WM_KEYDOWN / ToUnicodeEx to capture keystrokes and GetForegroundWindow / GetActiveWindowTitle to capture focused-window context, a SendBot/ChatID exfiltration pipeline, ProcessCritical (SetCurrentProcessIsCritical) anti-termination, an Uninstaller routine, a USBSpread module (USBThread/USBStart/USBCode) for removable-media propagation, a Plugin loader, and OpenUrl/ReportWindow/Monitoring command handlers. The package contains no legitimate library code; its sole install-time effect is delivering and running this binary on the installer's host.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for stellarfix (3 malicious versions).
If you installed it — respond
stellarfix 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 stellarfix 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 stellarfix-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.