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Malicious package

@coopeuch/confignpm

Advisory published Updated

@coopeuch/config is a confirmed malicious npm package (MAL-2026-17762) that opens a backdoor for remote access (malicious version 1.999.999). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @coopeuch/config (npm)

MAL-2026-17762
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall @coopeuch/config

What this malware does

The package publishes to the @coopeuch npm scope at version 1.999.999 with a stub index.js, a shape designed to win resolution over an internal scope registry when an organization's scope-to-registry mapping is missing. On npm install, scripts.postinstall executes postinstall.js, which collects host identity (hostname, username, uid/gid, homedir, non-internal network interface addresses and MAC addresses, DNS servers, reverse-DNS internal FQDN), CI/orchestration markers, npm context, container detection via /proc/1/cgroup, and the consuming parent package's name, version, and declared version range, then POSTs the aggregated JSON over HTTPS to the hardcoded author endpoint collector.oob.s4yhii.com/_npm-poc/beacon alongside a DNS beacon under *.oob.s4yhii.com. The behavior fires automatically at install time without consent and reveals internal infrastructure details and private project identifiers of any organization whose build resolves this package from the public registry.

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

1 flagged
1.999.999

Indicators of compromise (SHA-256)

0c9b2c76aac3e901d6585717a7e1f9729699bf3a4e280eb20a68bcef4d507d0d
7f05545d655ec4766414a523d3cf4dc6671cf72c67aefe8dd832dd59081bd23b

Detection & response playbook

Backdoor / remote access
  1. Find it

    Search your lockfiles and build artifacts for @coopeuch/config (version 1.999.999).

  2. If you installed it — respond

    @coopeuch/config establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

  3. Did it already run?

    If @coopeuch/config was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. @coopeuch/config on npm has been identified as a malicious package (version 1.999.999 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-021382GHSA-5w9x-2gg7-px58

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks @coopeuch/config-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Explore

@coopeuch/config (npm) malicious package — MAL-2026-17762 | O3 Security