layerd-unit-codec-parsernpm
layerd-unit-codec-parser is a confirmed malicious npm package (MAL-2026-6578) that opens a backdoor for remote access (malicious versions 1.0.0, 2.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in layerd-unit-codec-parser (npm)
What this malware does
The package presents itself as a CSS selector parser (src/selector-parser.js re-exports postcss-selector-parser; keywords postcss/selector/parser/css), but its main module also exposes run / runDefaultDecodedFunction / finalFinalDecodeAndRun. src/config/defaults.js ships an ~10KB opaque AES-GCM ciphertext (DEFAULT_FINAL_ENCODED_TEXT) alongside a hardcoded passphrase ("default-dev-passphrase"); src/aes/aes-gcm.js uses base64 Buffer decoding and scrypt to derive the key, decrypts the blob, and src/pipeline/custom-codec-pipeline.js invokes the plaintext as code through new Function("require", runnable)(require), granting the smuggled bytes full Node require/process capabilities. The package's own runtime/lib.min.js calls require("../src").run(), and package.json scripts (start, decode, test:cjs) plus a root cjs-runner.js funnel into the same decrypt-and-execute path. None of this is documented in the README, which describes only selector parsing and encode/decode helpers. A consumer who installs the package and runs the advertised npm start / decode scripts, or who imports and calls run(), executes the hidden payload. The combination of an opaque encrypted executable shipped in the tarball, a hardcoded key that makes the ciphertext functionally equivalent to shipping the code while evading source review, and an undocumented entry point that invokes it with full Node capabilities is a backdoor pattern. The postcss-selector-parser API mimicry increases the chance of the hidden run() path being reached.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for layerd-unit-codec-parser (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging layerd-unit-codec-parser across your stack and pipelines.
If you installed it — respond
layerd-unit-codec-parser 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 layerd-unit-codec-parser 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 layerd-unit-codec-parser 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks layerd-unit-codec-parser-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.