bigops-eslint-confignpm
Advisory published Updated
bigops-eslint-config is a confirmed malicious npm package (MAL-2026-12164) that executes malicious code on install (malicious version 35.1.9). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-eslint-config (npm)
What this malware does
The package presents itself as an ESLint config but on require() unconditionally loads vendor.js, which selects a platform-specific asset, fetches a binary via https.get from string-concatenation-obfuscated Cloudflare Workers hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf100-416.workers.dev), with a DNS-TXT chunked-base64 fallback to *.dl.wel1.ru (sdk/ext/pkg/net.dl.wel1.ru). The downloaded bytes are written to /var/tmp or %TEMP% under disguised names (.cache<hex>, dotnet_diag_<hex>.exe), chmodded 0755, and spawned detached via cp.spawn('/bin/sh', ['-c', fp+' &'], {detached:true}).unref(). Endpoint strings are assembled from array joins to evade static inspection; a sibling lib/telemetry.js uses require('child_' + 'process') and fs['chmod'+'Sync'] to further hide the sinks. The package name and 'environment config reader' description are unrelated to this behavior. No hash/signature verification, no version pinning, and the hosts are anonymous mutable infrastructure — arbitrary attacker code runs on the installer's host on import.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for bigops-eslint-config (version 35.1.9).
If you installed it — respond
Remove bigops-eslint-config 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-eslint-config was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks bigops-eslint-config-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.