sass-formatsnpm
sass-formats is a confirmed malicious npm package (MAL-2026-5629) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.2, 1.0.4, 1.0.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in sass-formats (npm)
What this malware does
The package name sass-formats is one character-edit away from the popular sass-formatter package and reuses its original author field ("author": "Syler" in package.json), while dist/cli.js carries a header indicating it was modified by a different maintainer (// Modified by https://github.com/maarutan... Marat Arzymatov 2025). The tarball ships dist/lib/lib.min.js, a heavily obfuscated 4 KB file that smuggles handles to require and module onto the global object (global['r']=require; global['m']=module), tags itself with a payload-version marker (global['_V']='A6-519-79'), and derives the string constructor from a shuffled character array to invoke Function(args, body) on a second shuffled string — the canonical string-array-shuffle / dynamic-Function execution shape used by npm credential and dropper malware. Although no entrypoint in v1.0.4 currently loads dist/lib/lib.min.js, shipping a hidden Function-constructor payload with smuggled require/module references in a package that purports to be a Sass formatter has no legitimate engineering purpose, and the combination of name-edit typosquat against sass-formatter plus impersonated author identity plus a staged dynamic-execution payload matches the supply-chain attack pattern.
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
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for sass-formats (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging sass-formats across your stack and pipelines.
If you installed it — respond
sass-formats is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If sass-formats 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 sass-formats 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 sass-formats-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.