Which versions of chalk-es are malicious?

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

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

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

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

Yes — chalk-es is associated with the IN-MAL-2026-018244 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-es 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-es (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-es across your stack and pipelines.

Malicious package

chalk-esnpm

chalk-es is a confirmed malicious npm package (MAL-2026-14166) 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-es (npm)

MAL-2026-14166

Immediate action

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

npm uninstall chalk-es

What this malware does

Package name mimics chalk but ships an empty library body; the only real behavior lives in scripts/postinstall.js. On install the script XOR-decodes (key stf2026) a hardcoded GitHub URL and downloads a Windows binary to %TEMP%\main.exe, then spawns it detached. On WSL/Linux hosts an XOR-decoded bridge command is exec'd to reach the underlying Windows host and run the same payload from inside Linux. The postinstall also POSTs a JSON body containing the resolved platform label (with WSL detection) to a hardcoded bare-IP endpoint at http://193.70.34.101:20099/vote, serving as an install beacon/victim tracker. Four byte-array constants (ADDON_ENC, BRIDGE_LAUNCHER_ENC, BRIDGE_SCRIPT_PRE_ENC, BRIDGE_SCRIPT_POST_ENC) are XOR-decoded at runtime specifically to hide the fetch URL and the Windows/WSL execution command.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

9a278b0c90f55a6a518b61ec1c964468011d1e4be184df5f36336a5f82ea58cc

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-es (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-es across your stack and pipelines.
If you installed it — respond
chalk-es 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-es 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-es 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-es 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-2026-018244

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks chalk-es-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

All malware advisories How O3 detects malware Vulnerability database