bigops-tslintnpm
bigops-tslint is a confirmed malicious npm package (MAL-2026-12848) that executes malicious code on install (malicious version 35.9.4). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-tslint (npm)
What this malware does
The package advertises itself as a lint tool but its index.js unconditionally require()s./ext, which on load selects a platform-specific payload path, downloads an opaque binary from one of several string-split-obfuscated Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf103-070.workers.dev) with a DNS TXT discovery fallback via *.dl.wel1.ru, writes it to /var/tmp or the Windows TEMP directory under a disguised filename, chmods it 0755, and spawns it detached through /bin/sh -c or cmd.exe. Host names and discovery domains are reconstructed at runtime from split string fragments (e.g. ["oob-w","ork","er.cf102-baf.work","ers.dev"].join("")) to defeat static analysis, and the module uses an environment-variable opt-out and a stamp-file TTL to reduce detection. A second dropper implementation with equivalent download+chmod+spawn logic is bundled as lib/telemetry.js (uses require("child"+"process"), fs["chmod"+"Sync"], and base64-reassembled bytes) and packaged alongside the live code path. The package purpose (a TypeScript lint tool) has no relationship to fetching and executing a native binary from anonymous Workers hosts. Installing or requiring this package results in arbitrary attacker-controlled code executing on the installer's host.
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
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigops-tslint (version 35.9.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-tslint across your stack and pipelines.
If you installed it — respond
Remove bigops-tslint from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If bigops-tslint 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 bigops-tslint 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 bigops-tslint-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.