Which versions of cobrowsing-cobrowsing-core are malicious?

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

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

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

If cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-core part of a known attack campaign?

Yes — cobrowsing-cobrowsing-core is associated with the IN-MAL-2026-015120 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 cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-core across your stack and pipelines.

Malicious package

cobrowsing-cobrowsing-corenpm

cobrowsing-cobrowsing-core is a confirmed malicious npm package (MAL-2026-12651) 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 cobrowsing-cobrowsing-core (npm)

MAL-2026-12651

Immediate action

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

npm uninstall cobrowsing-cobrowsing-core

What this malware does

[email protected] is a binary dropper disguised as a platform core package. On require()/import (index.js loads polyfill.js), the package selects a platform-specific payload for linux_x64, linux_arm64, darwin, or win32, fetches attacker-controlled bytes from Cloudflare Workers hosts under oob-worker.cf1xx-*.workers.dev, writes them to /var/tmp or %TEMP% under a disguised name (.cache<rand> on POSIX, dotnet_diag_<rand>.exe on Windows), chmods to 0755, and spawns them detached via /bin/sh -c or cmd.exe. No signature or hash verification is performed. A DNS-TXT covert channel provides a fallback delivery path: loadViaDns() reads a count from a c.<domain> TXT record, then concatenates N numbered TXT records from sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru, base64-decodes the result, and executes it. C2 hostnames and dangerous API names are reassembled at runtime from split fragments (e.g. ["oob-worker.cf103-070.w","ork","ers.","dev"].join(""), require("child_"+"process"), fs["chmod"+"Sync"]) as anti-scanner obfuscation. lib/telemetry.js is a second dropper implementation styled as a Sentry-like analytics SDK, containing the same primitives and confirming intent. Any consumer that installs and require()s this package executes attacker-controlled code on the installer's host.

Malicious versions

1 flagged

35.5.8

Indicators of compromise (SHA-256)

c27e38e295cce55b33b75d72a22db6deb6a851e7739111a1979f8317961465b9

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 cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-core across your stack and pipelines.
If you installed it — respond
cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-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 cobrowsing-cobrowsing-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. cobrowsing-cobrowsing-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-2026-015120

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks cobrowsing-cobrowsing-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

Explore

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