What does the caen-caen-core malware do?

The package's main entry (index.js) loads _ext.js on require. _ext.js downloads an OS-specific native binary from hardcoded Cloudflare Workers hosts (oob-worker.cf10{1,2,3}-*.workers.dev) with a DNS-TXT base64 fallback resolving via {sdk,ext,pkg,net}.dl.wel1.ru, writes it to /tmp or %TEMP% under deceptive names (.cache_ , dotnet_diag_ .exe), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. No hash or signature verification is performed. Hostnames are reconstructed at runtime by Array.join over split string fragments to evade static analysis, and the module presents an 'analytics'/telemetry cover story with DISABLE_TELEMETRY-style env gates. A secondary dropp

Which versions of caen-caen-core are malicious?

The following npm versions of caen-caen-core are flagged malicious: 35.5.8. Treat any of these as compromised.

How do I remediate caen-caen-core if I installed it?

caen-caen-core 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 caen-caen-core — how do I know if it already compromised me?

If caen-caen-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.

Is caen-caen-core part of a known attack campaign?

Yes — caen-caen-core is associated with the IN-MAL-2026-015243 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 caen-caen-core 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 caen-caen-core (version 35.5.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging caen-caen-core across your stack and pipelines.

Malicious package

caen-caen-corenpm

caen-caen-core is a confirmed malicious npm package (MAL-2026-12520) that opens a backdoor for remote access (malicious version 35.5.8). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in caen-caen-core (npm)

MAL-2026-12520

Immediate action

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

npm uninstall caen-caen-core

What this malware does

The package's main entry (index.js) loads ext.js on require. ext.js downloads an OS-specific native binary from hardcoded Cloudflare Workers hosts (oob-worker.cf10{1,2,3}-*.workers.dev) with a DNS-TXT base64 fallback resolving via {sdk,ext,pkg,net}.dl.wel1.ru, writes it to /tmp or %TEMP% under deceptive names (.cache<hex>, dotnet_diag<hex>.exe), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. No hash or signature verification is performed. Hostnames are reconstructed at runtime by Array.join over split string fragments to evade static analysis, and the module presents an 'analytics'/telemetry cover story with DISABLE_TELEMETRY-style env gates. A secondary dropper in lib/telemetry.js contains the same shape with additional obfuscation: require("child_" + "process"), Buffer.from(chunks, "base64"), fs["chmod"+"Sync"], and cp.spawn("/bin/sh", ["-c", filePath + " &"]). The fetched destinations and delivered binaries are unrelated to the stated 'platform core' purpose, giving whoever controls the C2 arbitrary code execution on any machine that installs or requires this package.

Malicious versions

1 flagged

35.5.8

Indicators of compromise (SHA-256)

bb26af904b5c17120eb2473e92815157757686f5dd47f19bd954a65224defbf6

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 caen-caen-core (version 35.5.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging caen-caen-core across your stack and pipelines.
If you installed it — respond
caen-caen-core 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 caen-caen-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 caen-caen-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

No. caen-caen-core on npm has been identified as a malicious package (version 35.5.8 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015243

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks caen-caen-core-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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