bigops-procedure-file-handlersnpm
bigops-procedure-file-handlers is a confirmed malicious npm package (MAL-2026-13233) that executes malicious code on install (malicious version 35.7.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-procedure-file-handlers (npm)
What this malware does
On require of the package, runtime.js downloads a platform-specific executable from obfuscated Cloudflare Workers endpoints (hostnames reassembled at runtime via array-join, e.g. oob-worker.cf99-9b3.workers.dev and sibling cf101/cf103/cf100 workers), writes it to /tmp or %TEMP% under a cover-story filename (dotnet_diag<tag>.exe on Windows,.cache_<tag> on Unix), chmods it to 0755, and detached-spawns it via /bin/sh -c or cmd.exe /c start /b. If HTTPS delivery fails, a fallback path queries DNS TXT records at subdomains of *.dl.wel1.ru, reads a chunk count from c.<host>, reassembles base64 chunks from N.<host> TXT records, and executes the resulting buffer. A stamp file.analytics_state is written to disguise the drop as OS/telemetry state. The obfuscation of destinations, covert DNS-TXT delivery channel, and disguised filenames indicate intentional evasion rather than legitimate telemetry or binary distribution.
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-procedure-file-handlers (version 35.7.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-procedure-file-handlers across your stack and pipelines.
If you installed it — respond
Remove bigops-procedure-file-handlers 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-procedure-file-handlers 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-procedure-file-handlers 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-procedure-file-handlers-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.