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Malicious package

vybscan-testbed-obfuscated-postinstallnpm

Advisory published Updated

vybscan-testbed-obfuscated-postinstall is a confirmed malicious npm package (MAL-2026-10079) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in vybscan-testbed-obfuscated-postinstall (npm)

MAL-2026-10079
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall vybscan-testbed-obfuscated-postinstall

What this malware does

package.json declares a postinstall lifecycle script that runs node -e "eval(Buffer.from('<base64>','base64').toString())". Installing the package triggers execution of code that is not visible in the package source and is only materialized at install time by decoding an opaque literal. In this specific version the decoded blob is an inert console.log, but the mechanism — obfuscated-then-eval'd bytes wired into a lifecycle hook — is the canonical install-time remote-code-execution shape and has no legitimate use: it lets whoever controls the package substitute arbitrary code at install without changing readable source. The package's self-description as a testbed fixture does not neutralize the pattern; the same install-time hook would execute whatever bytes were placed in the base64 literal.

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
1.0.0

Indicators of compromise (SHA-256)

cf9aee5b150e0606b1c5c2469fdab43496965a3dd5664df288d68d618e326567
cdace5e17981a8d6b102800b1bed41b0fddb5ebdbfa66e3751a07f3282ac9586

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for vybscan-testbed-obfuscated-postinstall (version 1.0.0).

  2. If you installed it — respond

    Remove vybscan-testbed-obfuscated-postinstall 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 vybscan-testbed-obfuscated-postinstall 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. vybscan-testbed-obfuscated-postinstall on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-009218GHSA-43r2-4jr2-rhjf

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks vybscan-testbed-obfuscated-postinstall-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.

Explore

vybscan-testbed-obfuscated-postinstall (npm) malicious package — MAL-2026-10079 | O3 Security