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Malicious package

browser-client-neptunenpm

Malicious code in browser-client-neptune (npm) Remove it immediately and rotate any exposed credentials.

MAL-2025-191484
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall browser-client-neptune

What this malware does

The package browser-client-neptune was found to contain malicious code.

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.

The OpenSSF Package Analysis project identified 'browser-client-neptune' @ 99.99.91 (npm) as malicious.

It is considered malicious because:

  • The package communicates with a domain associated with malicious activity.

Malicious versions

3 flagged
99.99.9199.99.9299.99.93

Indicators of compromise (SHA-256)

5b96b5ccfba68767c612c54af1007c61dcc8f73615000650cfb480ceffab949e
b9ad0cf7ca8faf91e654dc6ceb89ca235f191edc099334e5d8cf1a070bfb128a
b73a5ca8a0fe4b0bb753a26491a14177e8d3792f9510a203c634d6abe1f4d5cc
09450c3ace729a9541408c5b5834ccac03ee19f0739ae4ba7a818751a11de8ef
4ee66a30743d8a80934b9d50e852d2dcce63eb9df84b81a1b15a29c97138fd5c
640a584f26278ca2e3f146f9d5dd5a4ac36a9417821d1c5a16d7802214bc2192

Detection & response playbook

Malicious package
  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for browser-client-neptune (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging browser-client-neptune across your stack and pipelines.

  2. If you installed it — respond

    Remove browser-client-neptune 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.

  3. Did it already run?

    If browser-client-neptune 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.

  4. How O3 protects you

    O3 blocks browser-client-neptune 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

No. browser-client-neptune on npm has been identified as a malicious package (versions 99.99.91, 99.99.92, 99.99.93 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-367v-g33p-g8jc

References

Credits

  • Amazon Inspector · finder
  • OpenSSF: Package Analysis · finder

Detect & block this

O3 blocks browser-client-neptune-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.

browser-client-neptune (npm) malicious package — MAL-2025-191484 | O3 Security