bigops-legacy-utilsnpm
bigops-legacy-utils is a confirmed malicious npm package (MAL-2026-13222) that executes malicious code on install (malicious version 35.2.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-legacy-utils (npm)
What this malware does
On require('bigops-legacy-utils'), index.js loads polyfill.js which selects a platform-specific payload path, downloads opaque binary bytes from hardcoded Cloudflare workers.dev subdomains (oob-worker.cf103-070.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf100-416.workers.dev) with a DNS-TXT base64 fallback under *.dl.wel1.ru (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru), writes the payload to /var/tmp or %TEMP% under disguised names (.cache<suffix> on POSIX, dotnet_diag_<suffix>.exe on Windows), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. Destination hostnames are reassembled from split string fragments (e.g. ['sdk.dl.w','el1.ru'].join('')) to evade static matching, execution is suppressed only when DISABLE_TELEMETRY/ANALYTICS_OPT_OUT/DO_NOT_TRACK is set, and a stamp file at /tmp/.analytics_state throttles re-runs. Comments label the code as 'polyfill'/'analytics' as cover.
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-legacy-utils (version 35.2.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-legacy-utils across your stack and pipelines.
If you installed it — respond
Remove bigops-legacy-utils 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-legacy-utils 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-legacy-utils 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-legacy-utils-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.