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Malicious package

bigops-rx-post-messagenpm

Advisory published Updated

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)

MAL-2026-13248
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall bigops-rx-post-message

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

1 flagged
35.1.5

Indicators of compromise (SHA-256)

1298706de8e41561be6743e6d8349c5feefb81bec1ba71f3f2da3995d845ac98

Detection & response playbook

Malicious package

  1. Find it

    Search your lockfiles and build artifacts for bigops-rx-post-message (version 35.1.5).

  2. 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.

  3. Did it already run?

    If bigops-rx-post-message 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

No. bigops-rx-post-message on npm has been identified as a malicious package (version 35.1.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015747

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.

Malware detection Runtime egress monitoring

Explore

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bigops-rx-post-message (npm) malicious package — MAL-2026-13248 | O3 Security