bigops-watermarknpm
bigops-watermark is a confirmed malicious npm package (MAL-2026-12857) that executes malicious code on install (malicious version 35.9.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-watermark (npm)
What this malware does
On require() of the package, index.js unconditionally loads support.js, whose init() runs at module load. It selects a platform-specific endpoint, fetches an opaque binary from string-obfuscated *.workers.dev hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev) with DNS-TXT base64 fallbacks resolving to sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru, writes the payload to /tmp or %TEMP% under a disguised name (.cache<hex> or dotnet_diag_<hex>.exe), chmods it 0755, and spawns it detached via /bin/sh -c or cmd. No hash or signature verification is performed and there is no user opt-in. Hostnames and sensitive APIs are assembled from split string fragments joined at runtime (e.g. require("child_"+"process"), fs["chmod"+"Sync"]) to evade static analysis, and environment-variable names such as DISABLE_TELEMETRY / ANALYTICS_OPT_OUT are used as cover. A duplicate dropper implementation is also shipped in lib/telemetry.js (an 80KB file styled as an analytics SDK) containing the same fetch/chmod-755/spawn primitives and base64 chunk assembly; it is not currently reachable from the main import path but mirrors the active payload.
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
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigops-watermark (version 35.9.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-watermark across your stack and pipelines.
If you installed it — respond
Remove bigops-watermark 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-watermark 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-watermark 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks bigops-watermark-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.