nolbynpm
nolby is a confirmed malicious npm package (MAL-2026-10980) that typosquats a legitimate package to trick installs (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 nolby (npm)
What this malware does
The package advertises itself as a pure calendar/streak math library with no import-time side effects, but index.mjs invokes a top-level _sync() on module load. When loaded on a Linux process with access to /mnt/c (a WSL environment), the function enumerates Windows user profiles under /mnt/c/Users and writes the bundled cache.dat bytes to AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\vite-native-helper.exe under the first user's profile. The shipped cache.dat is a Windows PE executable (contains the !This program cannot be run in DOS mode stub and standard PE sections .rdata, .pdata, .reloc); it is declared in the files array as opaque data and renamed at write time to a Vite-lookalike filename. Placement in the Startup folder causes the PE to execute on the Windows user's next login, establishing persistent code execution on the WSL host's Windows side triggered by a normal require/import of the package.
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
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for nolby (4 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging nolby across your stack and pipelines.
If you installed it — respond
nolby is a typosquat — you almost certainly intended a legitimately-named package. Remove nolby, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If nolby 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 nolby 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 nolby-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.