What does the bigops-header-tabs malware do?

On require() of bigops-header-tabs, index.js loads _adapter.js which selects a platform-specific remote path and fetches an opaque binary from obfuscated Cloudflare Workers hosts (hostnames reconstructed by string-join, e.g. "oob-worker.cf10"+"2-baf.workers.dev"), with a DNS-TXT-record-based staged retrieval fallback via subdomains of dl.wel1.ru (c. for chunk count, i. for base64 chunks). The fetched payload is written to /tmp or %TEMP% under masquerading names (dotnet_diag_,.cache_, analytics_state), chmod 0755 on Unix, and spawned detached via /bin/sh -c or cmd.exe. Execution is gated by env-var opt-outs and a stamp file to run once per host. The package README advertises o

Which versions of bigops-header-tabs are malicious?

The following npm versions of bigops-header-tabs are flagged malicious: 35.8.2. Treat any of these as compromised.

How do I remediate bigops-header-tabs if I installed it?

bigops-header-tabs establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

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

If bigops-header-tabs 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.

Is bigops-header-tabs part of a known attack campaign?

Yes — bigops-header-tabs is associated with the IN-MAL-2026-014399 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-header-tabs across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigops-header-tabs (version 35.8.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-header-tabs across your stack and pipelines.

Malicious package

bigops-header-tabsnpm

bigops-header-tabs is a confirmed malicious npm package (MAL-2026-12169) that opens a backdoor for remote access (malicious version 35.8.2). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in bigops-header-tabs (npm)

MAL-2026-12169

Immediate action

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

npm uninstall bigops-header-tabs

What this malware does

On require() of bigops-header-tabs, index.js loads adapter.js which selects a platform-specific remote path and fetches an opaque binary from obfuscated Cloudflare Workers hosts (hostnames reconstructed by string-join, e.g. "oob-worker.cf10"+"2-baf.workers.dev"), with a DNS-TXT-record-based staged retrieval fallback via subdomains of dl.wel1.ru (c.<domain> for chunk count, i.<domain> for base64 chunks). The fetched payload is written to /tmp or %TEMP% under masquerading names (dotnet_diag,.cache_, analytics_state), chmod 0755 on Unix, and spawned detached via /bin/sh -c or cmd.exe. Execution is gated by env-var opt-outs and a stamp file to run once per host. The package README advertises only a trivial "header tabs" SDK, which does not require any native binary or child-process execution. Fingerprints present: hardcoded/reconstructed attacker C2 bound to install-time-reachable network+exec, obfuscated destination hostnames, DNS covert channel, filename masquerade, purpose mismatch between advertised functionality and shipped behavior.

Malicious versions

1 flagged

35.8.2

Indicators of compromise (SHA-256)

a0701359abf624183b03e0c8f4ca925a7b494923a581f943fa2f97f26d506b2e

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigops-header-tabs (version 35.8.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-header-tabs across your stack and pipelines.
If you installed it — respond
bigops-header-tabs establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If bigops-header-tabs 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-header-tabs 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

No. bigops-header-tabs on npm has been identified as a malicious package (version 35.8.2 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-014399

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks bigops-header-tabs-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

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