keplernpm
kepler is a confirmed malicious npm package (MAL-2026-13369) that executes malicious code on install (malicious versions 1.0.999, 1.999.999, 2.0.999…). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in kepler (npm)
What this malware does
[email protected] declares its only runtime dependency, flag-serial-object-syntax, as an HTTP URL to a third-party host (https://artifacts.yosiroute.com/npm/flag-serial-object-syntax) rather than a version resolved from the npm registry, and the shrinkwrap marks that dependency with hasInstallScript: true. Running npm install kepler fetches an unpinned, unverified tarball from artifacts.yosiroute.com and executes its lifecycle scripts on the installer's machine. The URL carries no version and no integrity metadata, so its contents can change at any time under the third-party host's control. The kepler package itself has placeholder metadata (author Package Registry, repository github.com/example/...) unrelated to the yosiroute.com host, and ships no first-party code that would justify sourcing a dependency off-registry. The dependency-tree-hijack shape — an off-registry, mutable, install-scripted tarball pulled in transitively — means any code the operator of artifacts.yosiroute.com serves runs with the privileges of the installer on npm install.
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
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for kepler (11 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging kepler across your stack and pipelines.
If you installed it — respond
Remove kepler 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 kepler 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 kepler 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 kepler-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.