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Malicious package

npm-show-date-proof-stringsnpm

Advisory published Updated

npm-show-date-proof-strings is a confirmed malicious npm package (MAL-2026-6791) that opens a backdoor for remote access (malicious versions 1.0.3, 1.0.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in npm-show-date-proof-strings (npm)

MAL-2026-6791
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall npm-show-date-proof-strings

What this malware does

The package's postinstall.js runs on every npm install and collects the installer's username (via whoami and os.userInfo()), hostname (os.hostname()), platform (process.platform), and Node version, then transmits them as query parameters via https.get() to a hardcoded endpoint at https://testnpm.byte.eyes.sh/npm-proof. The destination is author-controlled and undocumented; the installer has no opportunity to opt out. The package name ("npm-show-date-proof-strings") and an embedded NONCE string ("proof-2026-change-this-random-string") indicate this is a proof-of-execution beacon, but regardless of framing, it is unconsented host-identifier collection on install with no legitimate installer-facing purpose.

The OpenSSF Package Analysis project identified 'npm-show-date-proof-strings' @ 1.0.3 (npm) as malicious.

It is considered malicious because:

  • The package executes one or more commands associated with malicious behavior.

Malicious versions

2 flagged
1.0.31.0.4

Indicators of compromise (SHA-256)

a2ca450bd74580e87a2f428fd6fcfe66ac30e7a2a88e214da7d3628915549db6
2d30ee041cbe9a4b74e08cc0e493901460cc6563874723f620160c73908ed88a
884f2797ddf6247c906bb97e72b3c0891551b260980811d50c7211ab2ea0bbcf

Detection & response playbook

Backdoor / remote access

  1. Find it

    Search your lockfiles and build artifacts for npm-show-date-proof-strings (2 malicious versions).

  2. If you installed it — respond

    npm-show-date-proof-strings 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 npm-show-date-proof-strings 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. npm-show-date-proof-strings on npm has been identified as a malicious package (versions 1.0.3, 1.0.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-009370IN-MAL-2026-009563

References

Credits

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

Detect & block this

O3 blocks npm-show-date-proof-strings-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

All malware advisories How O3 detects malware Vulnerability database
npm-show-date-proof-strings (npm) malicious package — MAL-2026-6791 | O3 Security