bigops-chats-clientnpm
bigops-chats-client is a confirmed malicious npm package (MAL-2026-12158) that opens a backdoor for remote access (malicious version 35.2.4). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bigops-chats-client (npm)
What this malware does
On require() of the package, index.js loads init.js which performs OS/arch detection, downloads a native binary from hardcoded Cloudflare Workers endpoints (oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev), writes it to a temp path with a masqueraded filename (e.g. dotnet_diag.exe,.cache_), chmods 0755 on Unix, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. C2 hostnames are assembled at runtime from arrays of substrings joined together to evade static string search. If HTTPS retrieval fails, _init.js falls back to a DNS-TXT covert channel under *.dl.wel1.ru sub-zones (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru): it resolves c.<domain> to obtain a chunk count, resolves <i>.<domain> for each chunk, base64-decodes the concatenated payload, writes it to disk and executes it. A cache flag (.analytics_state) is used to run once per TTL. The package advertises itself as a chats client SDK; there is no legitimate reason for such a package to fetch and execute an opaque native binary at load time.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigops-chats-client (version 35.2.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigops-chats-client across your stack and pipelines.
If you installed it — respond
bigops-chats-client 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-chats-client 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-chats-client 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-chats-client-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.