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Malicious package

bigops-tinkoff-telephony-mocknpm

Advisory published Updated

bigops-tinkoff-telephony-mock is a confirmed malicious npm package (MAL-2026-12847) that typosquats a legitimate package to trick installs (malicious version 35.5.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bigops-tinkoff-telephony-mock (npm)

MAL-2026-12847
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall bigops-tinkoff-telephony-mock

What this malware does

On require() of the package, index.js loads runtime.js which fetches a platform-specific binary from Cloudflare Workers hosts (oob-worker.cf102-baf.workers.dev and siblings) reconstructed at runtime from split string fragments, with a DNS TXT covert-channel fallback under sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru. The fetched bytes are written to /tmp or %TEMP% under names disguised as.NET diagnostics files (dotnet_diag.exe,.cache_), chmod'd 0755, and executed detached via /bin/sh -c '<path> &' or cmd /c start. No hash or signature verification is performed, and the destination hosts are unrelated to the package publisher. A second copy of the same dropper is bundled under lib/telemetry.js wrapped as a fake Sentry-like telemetry SDK. The package name mimics a Tinkoff telephony mock but the shipped code is a full-host remote-code-execution dropper against any machine that installs or imports it.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Malicious versions

1 flagged
35.5.1

Indicators of compromise (SHA-256)

29cb54c5f503b1cad2b4ae932f592d8870df743b1c1b6b029616343b65f6ae09
38ba2813b46d8ed2bbdfceb6066bfecd7e32d7929f73906e88051b03ab1434c6

Detection & response playbook

Typosquat

  1. Find it

    Search your lockfiles and build artifacts for bigops-tinkoff-telephony-mock (version 35.5.1).

  2. If you installed it — respond

    bigops-tinkoff-telephony-mock is a typosquat — you almost certainly intended a legitimately-named package. Remove bigops-tinkoff-telephony-mock, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

  3. Did it already run?

    If bigops-tinkoff-telephony-mock 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-tinkoff-telephony-mock on npm has been identified as a malicious package (version 35.5.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015537GHSA-92wj-cj5h-gp6p

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks bigops-tinkoff-telephony-mock-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

All malware advisories How O3 detects malware Vulnerability database
bigops-tinkoff-telephony-mock (npm) malicious package — MAL-2026-12847 | O3 Security