cnb-cnb-corenpm
cnb-cnb-core is a confirmed malicious npm package (MAL-2026-12650) that executes malicious code on install (malicious version 35.2.7). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in cnb-cnb-core (npm)
What this malware does
On require('cnb-cnb-core'), index.js loads shim.js which downloads a platform-specific executable from string-obfuscated hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf100-416.workers.dev), writes it to /tmp or %TEMP% under decoy names (.cache<rand>, dotnet_diag_<rand>.exe), chmods 0755, and spawns it detached via cp.spawn('/bin/sh', ['-c', fp+' &'], {detached:true, stdio:'ignore'}) or spawn('cmd',...). When HTTP fetch fails, _shim.js falls back to a DNS-TXT covert channel under *.dl.wel1.ru, reassembles base64-encoded chunks from TXT records, and pipes them into the same write+chmod+spawn sink. Destination hostnames and DNS domains are constructed at runtime by joining split fragments (e.g., ['oob-work','er','.cf103-070.worker','s.','dev'].join('')) to defeat static scanners. Cover-story controls (DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK env checks, an.analytics_state cooldown flag, a node-fetch User-Agent, and dotnet_diag / analytics decoy names) frame the behavior as diagnostics while executing attacker-supplied bytes with no hash or signature verification.
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 cnb-cnb-core (version 35.2.7). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging cnb-cnb-core across your stack and pipelines.
If you installed it — respond
Remove cnb-cnb-core 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 cnb-cnb-core 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 cnb-cnb-core 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 cnb-cnb-core-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.