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Malicious package

express-bunkernpm

Advisory published Updated

express-bunker is a confirmed malicious npm package (MAL-2026-10500) that opens a backdoor for remote access (malicious version 6.1.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in express-bunker (npm)

MAL-2026-10500
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall express-bunker

What this malware does

[email protected] ships a postinstall script that performs an HTTP GET to a hardcoded bare IP over plain HTTP (http://130.49.177.51:18080/p/dc-20260627-yandex-geobase) at npm install time, transmitting the package name, version, and a fixed campaign nonce (bb-express-bunker-20260628). The beacon fires unconditionally on every install with no opt-out. The package name and beacon path indicate a dependency-confusion squat against an internal namespace (yandex-geobase): any host or CI system that mis-resolves an internal dependency name to this public artifact silently signals successful name shadowing to the operator-controlled endpoint, disclosing installer environment information and confirming exploitability for follow-on attacks. A README self-label as a 'benign PoC' does not change the installer-side effect — the public artifact performs install-time outbound network I/O the installer did not opt into, and the same install vector could ship arbitrary code in a later version.

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
6.1.0

Indicators of compromise (SHA-256)

68139b9a62e1d546de6ce2e46d5203782dbf54f1af2edbd2b8f509528eb0f000
27082ec28738f103f3d79213fcec51b4d66b71e422642ca9d530b3d005858f52
5002727bea69ce0b5c286859dcc28a658fe477dde499a97e366d77f35fb31dc1
a3bdfa5e0db2d141c2bfeae86050264a91c3945dafe6f94fcfb4350403861061

Detection & response playbook

Backdoor / remote access
  1. Find it

    Search your lockfiles and build artifacts for express-bunker (version 6.1.0).

  2. If you installed it — respond

    express-bunker 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 express-bunker 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. express-bunker on npm has been identified as a malicious package (version 6.1.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-010324GHSA-w7r5-8cmj-m893RLMA-2026-06231RLUA-2026-10732

References

Credits

  • Amazon Inspector · finder
  • ReversingLabs · finder

Detect & block this

O3 blocks express-bunker-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

express-bunker (npm) malicious package — MAL-2026-10500 | O3 Security