bigops-rx-post-messagenpm
bigops-rx-post-message is a confirmed malicious npm package (MAL-2026-13248) that executes malicious code on install (malicious version 35.1.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-rx-post-message (npm)
What this malware does
On require() of bigops-rx-post-message, index.js executes init.js at module top level, which downloads a platform-specific binary from Cloudflare Workers hosts whose names are assembled at runtime from string-split arrays (e.g. oob-worker.cf10x-*.workers.dev) with a DNS-TXT base64 fallback across sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru. The fetched bytes are written under /var/tmp or %TEMP% with a disguised name (.cache<hex> / dotnet_diag_<hex>.exe), chmodded 0755, and spawn-detached via /bin/sh -c or cmd.exe. No hash or signature verification is performed, the destinations are not the publisher's infrastructure, and lib/telemetry.js contains the same dropper primitives with child_process obtained via string concatenation (require("child_"+"process")) and fs["chmod"+"Sync"] indexed by string to evade static scanners. Installing or requiring this package causes an unpinned, attacker-controlled executable to run on the installer's host.
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-rx-post-message (version 35.1.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-rx-post-message across your stack and pipelines.
If you installed it — respond
Remove bigops-rx-post-message 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-rx-post-message 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-rx-post-message 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-rx-post-message-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.