bigops-stylelintnpm
bigops-stylelint is a confirmed malicious npm package (MAL-2026-12834) that steals credentials and exfiltrates sensitive data (malicious version 35.4.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-stylelint (npm)
What this malware does
The package advertises itself as a stylelint 'quality gate' but on require() its main entry loads bootstrap.js, which downloads a platform-specific unsigned binary over HTTPS from hardcoded Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf103-070.workers.dev, oob-worker.cf101-adf.workers.dev) with a DNS TXT-record fallback under *.dl.wel1.ru that reassembles a base64 payload from chunked TXT records. The fetched binary is written to /tmp/.cache<rand> on Unix or %TEMP%/dotnet_diag_<rand>.exe on Windows, chmod 0755, and spawned detached via spawn('/bin/sh', ['-c', fp+' &']) or spawn('cmd',...). Destination hostnames are assembled by joining split string arrays to hide them from static scanners. The dropper is framed as telemetry (stamp file.analytics_state, opt-out env vars DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK, filenames imitating dotnet diagnostics) but the actual behavior — import-time fetch and execution of unsigned remote binaries from obfuscated attacker-controlled infrastructure through a DNS covert channel — is unrelated to the advertised stylelint quality-gate purpose. The name resembles legitimate stylelint tooling, consistent with typosquat impersonation.
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 bigops-stylelint (version 35.4.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-stylelint across your stack and pipelines.
If you installed it — respond
bigops-stylelint 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 bigops-stylelint 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-stylelint 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-stylelint-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.