velocityfixnpm
velocityfix is a confirmed malicious npm package (MAL-2026-6487) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.0, 1.0.1, 1.0.2…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in velocityfix (npm)
What this malware does
Package masquerades as 'Performance fixes for Minecraft Velocity proxy' authored by 'Velocity Team' — Velocity is a Java project from PaperMC and has no legitimate npm distribution. package.json declares scripts.postinstall = 'node scripts/loader.js', which silently spawns a bundled payload.exe via start /b on every npm install. The bundled PE contains a hardcoded C2 at https://751.lol/upload/ and posts a multipart form with fields username, os_info, ip_address, and file=data.zip — exfiltrating the installer's hostname, OS, IP, and a zip of collected files to an attacker-controlled host. The payload labels itself [INJECTOR], reads registry values (ProductName, DisplayVersion), and performs sandbox / VM evasion (probes for SbieDll.dll, snxhk.dll, Vboxguest.sys, vmGuestLib.dll, VMware/VirtualBox artifacts) so it only fully detonates on real victim hosts. The combination of brand-impersonation lure, install-time auto-execution of an opaque native binary, hardcoded exfil endpoint, and anti-analysis evasion is an unambiguous Windows-targeted supply-chain dropper.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for velocityfix (5 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging velocityfix across your stack and pipelines.
If you installed it — respond
velocityfix 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 velocityfix was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks velocityfix before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks velocityfix-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.