Which versions of bigops-cobrowsing are malicious?

The following npm versions of bigops-cobrowsing are flagged malicious: 35.4.9. Treat any of these as compromised.

How do I remediate bigops-cobrowsing if I installed it?

Remove bigops-cobrowsing 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.

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

If bigops-cobrowsing 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-cobrowsing part of a known attack campaign?

Yes — bigops-cobrowsing is associated with the IN-MAL-2026-014417 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-cobrowsing across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for bigops-cobrowsing (version 35.4.9).

Malicious package

bigops-cobrowsingnpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

bigops-cobrowsing is a confirmed malicious npm package (MAL-2026-12159) that executes malicious code on install (malicious version 35.4.9). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bigops-cobrowsing (npm)

MAL-2026-12159

Immediate action

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

npm uninstall bigops-cobrowsing

What this malware does

On require of the package's main entry, compat.js selects a per-OS asset path and downloads a native binary from one of three anonymous *.workers.dev hosts (oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf103-070.workers.dev), with a DNS TXT-record fallback resolving sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru to obtain a substitute host. The fetched bytes are written to a temp path under a disguised name (dotnet_diag<rand>.exe on Windows,.cache_<rand> on Unix), chmod 0755, and executed detached via spawn("cmd",...) or spawn("/bin/sh", ["-c", fp+" &"]). Destination hostnames are reassembled at runtime via array.join("") string-split obfuscation (e.g. ["oob-worker.cf99-9b3.workers",".de","v"].join(""); ['sdk.dl.wel','1.r','u'].join("")). No publisher-matching source, no version pin, no hash/signature verification; declared purpose is a cobrowsing library, which does not require fetching and executing an opaque native binary from anonymous infrastructure.

Malicious versions

1 flagged

35.4.9

Indicators of compromise (SHA-256)

e81463953e6dde1f029deb6a15345c1f0e1a763e59c2f52e821c8e6f2d62f379

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for bigops-cobrowsing (version 35.4.9).
If you installed it — respond
Remove bigops-cobrowsing 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-cobrowsing 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-cobrowsing on npm has been identified as a malicious package (version 35.4.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-014417

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks bigops-cobrowsing-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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