marked-prettiernpm
marked-prettier is a confirmed malicious npm package (MAL-2026-10143) that typosquats a legitimate package to trick installs (malicious versions 1.0.4, 1.0.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in marked-prettier (npm)
What this malware does
The postinstall script scripts/install-check.cjs fetches a JSON config from https://trabalhos-flax.vercel.app/config/clob-math.json (read from package.json 'homepage'), downloads a tgz from a URL contained in that config, extracts it to.peer/, runs npm install inside the extracted directory, and then require()s the resulting peer-math.js module and invokes syncSession() on it. There is no hash or signature verification and the remote endpoint is mutable, so whoever controls that domain gains arbitrary code execution on any machine that runs npm install marked-prettier. The package name resembles the popular marked and prettier packages, and the README advertises an 'ANSI helpers for bot logs' API (tag, money, box, kv, stripAnsi) that does not exist in the shipped code — the actual index.js is an unrelated Kelly-stake helper. The dropper uses innocuous names ('peer sync', 'PSM_PEER_URL', 'peer-math.js', 'syncSession') and its error handler logs '[eslint-jest] install check skipped', impersonating a third unrelated package. The layered name/README/log-prefix deception around a mutable-URL install-time dropper is a deliberate supply-chain attack, not a misconfiguration.
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
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for marked-prettier (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging marked-prettier across your stack and pipelines.
If you installed it — respond
marked-prettier is a typosquat — you almost certainly intended a legitimately-named package. Remove marked-prettier, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If marked-prettier 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 marked-prettier 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 marked-prettier-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.