Which versions of post-css-transfer are malicious?

The following npm versions of post-css-transfer are flagged malicious: 0.0.1. Treat any of these as compromised.

How do I remediate post-css-transfer if I installed it?

post-css-transfer 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 post-css-transfer — how do I know if it already compromised me?

If post-css-transfer 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 post-css-transfer part of a known attack campaign?

Yes — post-css-transfer is associated with the IN-MAL-2026-014753, GHSA-f5h9-q436-8chv 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 post-css-transfer 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 post-css-transfer (version 0.0.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging post-css-transfer across your stack and pipelines.

Malicious package

post-css-transfernpm

post-css-transfer is a confirmed malicious npm package (MAL-2026-12417) that opens a backdoor for remote access (malicious version 0.0.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in post-css-transfer (npm)

MAL-2026-12417

Immediate action

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

npm uninstall post-css-transfer

What this malware does

post-css-transfer is a typosquat of postcss whose main entry lib/postcss.js has an obfuscated IIFE appended after the legitimate module code. On require/import, the appended block resolves a command-and-control IP by reading transactions of Ethereum address 0xa322E5f3D311D3080e6f0121063e9aDC2490Ef1a via public Ethereum RPC endpoints and the eth.blockscout.com API, decodes two IPv4 addresses from the transaction recipient bytes, fetches an XOR-encrypted payload over HTTP from those hosts (delivered in an x-payload-b64 header), and executes the decrypted payload via eval() and a detached node -e child process. Network, execution, and identifier primitives (http, child_process, spawn, the Ethereum address, method and header names) are written as \uXXXX escapes and hidden behind ~1KB of whitespace padding after module.exports = postcss; to evade casual review.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Malicious versions

1 flagged

0.0.1

Indicators of compromise (SHA-256)

f62ccc235772a34a28d870f349489698c167e3d636a196f310fe24c1ce1d4ef4

3e35af1cb71e17048626ceebf0ea0022262f7bfbbfd82cedf4c9ee5c19bfaa76

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 post-css-transfer (version 0.0.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging post-css-transfer across your stack and pipelines.
If you installed it — respond
post-css-transfer 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 post-css-transfer 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 post-css-transfer 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. post-css-transfer on npm has been identified as a malicious package (version 0.0.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-014753GHSA-f5h9-q436-8chv

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks post-css-transfer-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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