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Malicious package

hex-typenpm

Malicious code in hex-type (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-5538
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall hex-type

What this malware does

Package metadata (description "A universally-unique, lexicographically-sortable, identifier generator", homepage github.com/ulid/javascript, build script --name ulidx, reused ULID source) impersonates the legitimate ulid/ulidx libraries, but the package adds a malicious dropper not present in those projects. package.json declares "postinstall": "node dist/utils.js". On npm install, dist/utils.js re-spawns itself detached with --bg, copies dist/payload.js (~950KB) to a hidden directory named MicrosoftSystem64 under LOCALAPPDATA / Application Support / ~/.local/share (impersonating a Windows system component), and registers OS-level persistence: a Windows Scheduled Task plus Run-key launching wscript.exe of a generated VBS, a Linux systemd --user service with loginctl enable-linger, or a .config/autostart fallback, and a detached spawn on macOS. The dropped payload.js bundles the ws WebSocket client/server, pino logging, zod, and references https://huggingface.co/api and https://huggingface.co — the building blocks of a long-running remote-controlled agent, with zero relation to ULID generation. Both the postinstall (if (cpus.length <= 4...) return;) and the agent (MIN_CPU_COUNT = 5) abort on hosts with ≤4 CPUs to evade sandboxes and low-core CI runners. This is unambiguous installer-side RCE plus persistence plus C2.

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

1 flagged
3.0.2

Indicators of compromise (SHA-256)

1b9530df5da36f6e3de0761c79ef3687e4f0c5f1990d77a3f874df2c1b3fe278
f7d0271fe97ea66e9ff2ba3a0ea225364324f28138af32c337d6ed8b2b99e5ad
4a9a7e2427ae3c6ab1b50874653afe275962d527b94bf81ea5ce52ae9455d793

Detection & response playbook

Backdoor / remote access
  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for hex-type (version 3.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging hex-type across your stack and pipelines.

  2. If you installed it — respond

    hex-type 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.

  3. Did it already run?

    If hex-type 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.

  4. How O3 protects you

    O3 blocks hex-type 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

No. hex-type on npm has been identified as a malicious package (version 3.0.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-005342IN-MAL-2026-005341GHSA-jc42-pxfc-29x3

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks hex-type-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Explore

hex-type (npm) malicious package — MAL-2026-5538 | O3 Security