What does the bigops-watchdog-worker malware do?

On require() of bigops-watchdog-worker, index.js loads _runtime.js which reconstructs remote hostnames from split-string fragments (e.g. joining ["oob-w","orker.cf102-baf.workers.d","ev"] and ['sdk.dl.wel1','.ru']), selects a URL keyed on process.platform/arch (linux_x64, linux_arm64, darwin, win32), downloads opaque binary bytes over HTTPS, writes them to /tmp/.cache_ on Unix or %TEMP%\dotnet_diag_ .exe on Windows (masquerading as a Microsoft diagnostic), chmods 0755, and spawns the binary detached via /bin/sh -c or cmd.exe. A DNS TXT chunked-record fallback reassembles a base64 payload if HTTPS fails. Anti-analysis features include a cache stamp at /tmp/.analytics_state that suppr

Which versions of bigops-watchdog-worker are malicious?

The following npm versions of bigops-watchdog-worker are flagged malicious: 35.7.4. Treat any of these as compromised.

How do I remediate bigops-watchdog-worker if I installed it?

bigops-watchdog-worker is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed bigops-watchdog-worker — how do I know if it already compromised me?

If bigops-watchdog-worker 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.

Is bigops-watchdog-worker part of a known attack campaign?

Yes — bigops-watchdog-worker is associated with the IN-MAL-2026-015527, GHSA-832x-jg38-259f campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find bigops-watchdog-worker across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for bigops-watchdog-worker (version 35.7.4).

Malicious package

bigops-watchdog-workernpm

Advisory published Aug 5, 2026Updated Aug 6, 2026

bigops-watchdog-worker is a confirmed malicious npm package (MAL-2026-12856) that steals credentials and exfiltrates sensitive data (malicious version 35.7.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bigops-watchdog-worker (npm)

MAL-2026-12856

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall bigops-watchdog-worker

What this malware does

On require() of bigops-watchdog-worker, index.js loads runtime.js which reconstructs remote hostnames from split-string fragments (e.g. joining ["oob-w","orker.cf102-baf.workers.d","ev"] and ['sdk.dl.wel1','.ru']), selects a URL keyed on process.platform/arch (linux_x64, linux_arm64, darwin, win32), downloads opaque binary bytes over HTTPS, writes them to /tmp/.cache<uid> on Unix or %TEMP%\dotnet_diag_<uid>.exe on Windows (masquerading as a Microsoft diagnostic), chmods 0755, and spawns the binary detached via /bin/sh -c or cmd.exe. A DNS TXT chunked-record fallback reassembles a base64 payload if HTTPS fails. Anti-analysis features include a cache stamp at /tmp/.analytics_state that suppresses re-execution for ~23000 seconds and honors DISABLE_TELEMETRY/ANALYTICS_OPT_OUT/DO_NOT_TRACK env vars to appear benign under inspection. Neither oob-worker.*.workers.dev nor *.dl.wel1.ru is a publisher-controlled or publisher-adjacent host.

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

35.7.4

Indicators of compromise (SHA-256)

a65df39f269239434211427140c77c096d41d8de8800667ef39a27bf89572c67

9e49dcb46de2cb5a5eba07bfeb572af91a97b3c6749a13d0667d7a64fe0c4a82

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for bigops-watchdog-worker (version 35.7.4).
If you installed it — respond
bigops-watchdog-worker is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If bigops-watchdog-worker 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-watchdog-worker on npm has been identified as a malicious package (version 35.7.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015527GHSA-832x-jg38-259f

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks bigops-watchdog-worker-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database