bnpl-blocks-post-cssnpm
bnpl-blocks-post-css is a confirmed malicious npm package (MAL-2026-13013) that executes malicious code on install (malicious version 35.5.4). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in bnpl-blocks-post-css (npm)
What this malware does
On require(), polyfill.js reconstructs attacker-controlled hostnames from string-split fragments (oob-worker.cf103-070.workers.dev, with a DNS-TXT fallback via sdk.dl.wel1.ru), downloads a platform-specific native binary, writes it to /tmp or %TEMP% under a disguised name (.cache<hex> on Unix, dotnet_diag_<hex>.exe on Windows), chmods it 0o755, and spawns it detached via spawn('/bin/sh', ['-c', <path> + ' &'], {detached:true}) or the cmd equivalent. lib/telemetry.js contains a second implementation of the same fetch->write->chmod 755->spawn pattern with a base64-decoded payload under an analytics-SDK cover story. The package is advertised as a CSS-blocks utility and has no legitimate reason to fetch and execute native binaries; the string-split obfuscation of the download hosts and the 'analytics_state' / DISABLE_TELEMETRY cover-story naming further confirm hostile intent.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bnpl-blocks-post-css (version 35.5.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bnpl-blocks-post-css across your stack and pipelines.
If you installed it — respond
Remove bnpl-blocks-post-css from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If bnpl-blocks-post-css 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 bnpl-blocks-post-css 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 bnpl-blocks-post-css-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.