index-ulidnpm
index-ulid is a confirmed malicious npm package (MAL-2026-5827) that opens a backdoor for remote access (malicious versions 3.0.2, 3.0.3, 3.0.4). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in index-ulid (npm)
What this malware does
index-ulid impersonates the legitimate ulid/ulidx ULID generator (reuses ulid's description and links its homepage to github.com/ulid/javascript) but its postinstall script (package.json line 36: node dist/node/utils.js) is a cross-platform dropper. utils.js detaches with --bg, copies the bundled dist/node/payload.js into a directory named MicrosoftSystem64 under the user's data-local directory (utils.js:7 var UNIT_STEM = "MicrosoftSystem64") to disguise it as a Microsoft system component, then installs persistence on every major OS: Windows schtasks /create /sc ONLOGON (with a Registry Run key fallback), macOS detached spawn, and Linux systemd --user service or ~/.config/autostart. The dropped binary is then launched in the background as node payload.js --agent (utils.js:75-79 spawn(process.execPath, [jsPath, "--agent"], { detached: true })). The 949 KB payload.js bundles a WebSocket client/server (ws), pino, zod, and contains string references to /api/validate, /api/hf, https://huggingface.co/api, and Telegram — a long-running C2 agent that beacons to remote services from every installer host. Both the postinstall and the agent contain a sandbox-evasion CPU gate (utils.js:155 skips when cpus.length <= 4; payload.js cpu-guard sets MIN_CPU_COUNT = 5 and exits otherwise) so the dropper only fires on real developer/server machines and stays silent in malware sandboxes and small CI runners. None of this behavior is justified by a ULID library; the package is a typosquat lure for a persistent backdoor.
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
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for index-ulid (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging index-ulid across your stack and pipelines.
If you installed it — respond
index-ulid establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If index-ulid 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 index-ulid 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
- ReversingLabs · finder
Detect & block this
O3 blocks index-ulid-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.