Which versions of chalk-core are malicious?

The following npm versions of chalk-core are flagged malicious: 1.0.0. Treat any of these as compromised.

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

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

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

Yes — chalk-core is associated with the IN-MAL-2026-018246 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 chalk-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 chalk-core (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging chalk-core across your stack and pipelines.

Malicious package

chalk-corenpm

chalk-core is a confirmed malicious npm package (MAL-2026-14165) that opens a backdoor for remote access (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in chalk-core (npm)

MAL-2026-14165

Immediate action

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

npm uninstall chalk-core

What this malware does

[email protected] typosquats the popular chalk package but ships no chalk functionality — index.js exports an empty object. Its only behavior is in scripts/postinstall.js, which runs automatically on npm install. The script XOR-decodes (key 'stf2026') a hidden URL that resolves to a github.com download, fetches an executable to %TEMP%\main.exe on Windows, and launches it detached (spawn with detached:true, stdio:'ignore', windowsHide:true) with no hash or signature verification. When running under WSL, isVirtualizedLinux() inspects /proc/version, /proc/sys/kernel/osrelease, and WSL_DISTRO_NAME / WSLENV, then exec()s a XOR-decoded bridge command that reaches out of the Linux guest to the Windows host to fetch and execute the same payload. Before the drop, postinstall assembles the bare IPv4 193.70.34.101 from a string-array literal ['193','70','34','101'].join('.') and POSTs the host platform to http://193.70.34.101:20099/vote — an install-tracker/kill-switch beacon on a non-standard port. Four separate XOR-encoded byte-array constants (ADDON_ENC, BRIDGE_LAUNCHER_ENC, BRIDGE_SCRIPT_PRE_ENC, BRIDGE_SCRIPT_POST_ENC) hide the download URL and shell commands from casual inspection.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

fbf1ccbcd9b3ae6643a7948154a981ef7e072afbae6d9611f832df11fccc6707

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 chalk-core (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging chalk-core across your stack and pipelines.
If you installed it — respond
chalk-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 chalk-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 chalk-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. chalk-core on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-018246

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks chalk-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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